SUNBOOK 33

SUNBOOKSUNBOOKSUNBOOKSUNBOOKSUNBOOKA Guide to Solar Energy in North Carolina

Revised in 1999 by the N.C. Solar Center with funding providedby the Energy Division, N.C. Department of Commerce.

TABLE OF CONTENTS

INTRODUCTION

Does a Switch to Solar Energy Make Sense? Page 1

CHAPTER 1How Much Sun is Enough for Heating? Page 2

CHAPTER 2Collecting the Sun's Heat Page 3

CHAPTER 3The Sun and a Little Engineering Help Page 5

CHAPTER 4Passive Solar Design Page 10

CHAPTER 5Passive Cooling Techniques Page 16

CHAPTER 6Low-Cost Solar Heaters Page 17

CHAPTER 7Photovoltaics for the Homeowner Page 20

CHAPTER 8Consumer Tips Page 21

RESOURCE ORGANIZATIONS PAGE 23

BIBLIOGRAPHY PAGE 28

SUNBOOK 38

Originally prepared with funds from the Southern Solar Energy Center.Reprinted in 1999 entirely in Adobe Acrobat with recycled electrons.

0,000 copies of this public document were printed at a cost of $0,000 or $0.00 each.

SUNBOOK 1

INTRODUCTIONDOES A SWITCH TO SOLAR ENERGY MAKE SENSE?

Yes! The technology is available today—and it is getting better and better

As prices go up for electricity, oil, natural gasor propane, we tighten our belts just a little bitmore. In North Carolina, the cost of heatingand cooling a home in recent years has risenfaster than any other basic commodity. Somefamilies are getting monthly utility bills thatare higher than their mortgage payments.

Yet other North Carolinians are payingas little as $50 to heat their homes for an entirewinter. How do they do it?

To be sure, they have cut their utilitybills with a combination of good conservationmeasures and habits. However, most of theirsavings have come about because they havestarted using solar energy in their homes.

Solar energy is in North Carolina to stay.As of 1996, thousands of homes in the stateare heated by the sun and more than 25,000additional homes rely on solar energy to providemost of their hot water throughout the year.

North Carolina has a generous solartax credit for businesses, homeowners, andindustry. North Carolina also has available alarge and growing network of solar energydealers and installers and several equipmentmanufacturers. You can look in almost anytelephone book and find a company thatdesigns, sells or maintains solar energy sys-tems. However, you may find it difficultknowing which is best for your needs. Evenknowing what questions to ask is not easy.

Sunbook will help you determine yourhome’s solar potential and what type of systembest suits your needs, lifestyle and pocketbook.There is also a chapter on consumer protec-tion. Finally, there’s a bibliography and listingof organizations involved in solar researchand education. We hope it all helps you gaina better understanding of solar energy and itspotential in your home.

SUNBOOK 2

32 degrees and 45 degrees above the horizonand sets to the south of west. In summer, thesun is up 12 to 14 hours and is almost directlyoverhead.

To get an accurate picture of the availablesunlight at any particular location, use a sunchart such as the one shown on this page. Suncharts show the sun's path at different times ofthe day and year for a given latitude. When thechart is printed on clear plastic and mountedon a viewing stand—usually consisting ofa wide-angle lens, a compass and a level—a homeowner can observe the sky from thepoint where the solar system is to be locatedand determine if neighboring trees or buildingswill block the sun. While you can constructyour own viewfinder, you may want to talk toa local solar equipment dealer about checkingyour home's solar potential.

To take good advantage of solar power,you need access to direct sunlight in the areaabove the altitude sun angle for December 21and at a maximum, 60 degrees both east andwest of true south. This corresponds roughlyto having an unobstructed view of the sunbetween 9 a.m. and 3 p.m. from late Septem-ber to late March. Remember, these are idealconditions. A partially obstructed view stillcan provide a great deal of solar heat.

CHAPTER 1HOW MUCH SUN IS ENOUGH FOR HEATING ?See If Your House Gets Enough Direct Sun

It is difficult to find anyone today who doesn’tthink that solar energy is a good idea. Butwhether or not solar energy is a wise invest-ment for you depends on several factors. Forinstance, there are only a few low-cost solardevices that are worth investigating if you livein rental housing. If you own your home, yourhouse must be relatively energy efficient beforeany solar system will perform up to its poten-tial. Insulation, caulking and weatherstrippingwill save more money than a solar system andusually costs less.

You also need a relatively open viewof the sky to the south of your home, at leastduring the winter months. The drawing on thispage shows the path of the sun on December21, the shortest day of the year, and June 21,the longest day of the year. During the shortwinter days, we get only nine to eleven hoursof sunlight in North Carolina. The sun risesslightly to the south of east, climbs to between

Fig. 1: A sun chart for 36 degrees north latitude.

SUNBOOK 3

greenhouse effect when you got into your caron a hot summer day with the windows rolledup. The sunlight that passed through thewindow glass was converted into heat afterstriking the inside of the car. Heat—thermalradiation—cannot easily escape, so air tem-peratures in the car rise, eventually going farabove outdoor temperatures.

ACTIVE SOLAR SYSTEMS

Solar collectors are designed to take advan-tage of the greenhouse effect. The flat-platecollector, used for most solar space and waterheating applications, is essentially an insulatedmetal box with a glass or plastic cover. Ablack metal absorber plate with tubes orchannels for the passage of the heat transfer

medium is located withinthe box (Figure 4).

The heat transfermedium is nothing morethan hot air or a hot liquidthat transfers solar energyfrom a collector to a heatstorage unit and then to thehome’s living quarters.When tilted at the properangle in relation to the sun,sunlight will pass throughthe glass cover, strike theabsorber plate and beconverted to heat. Thecollector, insulated on thebottom and sides, preventsmost of the heat fromescaping.

Typically, a collectorwill be mounted on the roofof a building, where it willget the most exposure tosunlight. This type of designis referred to as an “active”solar system (Figure 2). Itis called active because itrequires electrically pow-ered pumps or fans tooperate. In fact, active

CHAPTER 2COLLECTING THE SUN’S HEAT

The Key: Storing Heat Your System Collects

The term “solar system” refers to a combina-tion of items working together to providespace heat or hot water. To work, solarsystems need a means of collecting solar heat,a means of controlling and distributing heatand, in most cases, a means of storing heat.

The collection of solar energy is madepossible by what is known as the “greenhouseeffect.” You have experienced firsthand the

Fig. 2: Cut-away drawing of an active solar heated house.

Flat Plate Collectors

Cold Waterto Collector

Hot Waterfrom Collector

HVAC AirHandling Unit

Hot WaterTank Solar Storage

Tank

Cold Waterfrom CityMain

Hot Waterto Household

Water to HeatExchangerCoil

SUNBOOK 4

systems may be thought of as solar appliancesbecause of their similarity to conventionalheating and hot water systems.

Usually, your household will need themost heat when the sun is down at night andtemperatures are colder. You will need theleast heat during the day when sunshine isabundant. A system that stores solar heat forlater use will thus be able to provide more ofyour home’s heating needs than one withoutstorage. In an active solar system that uses airas the transfer medium, heat usually is storedin an insulated rock bin or an air-cored ma-sonry wall in the house. Liquid solar systemsusually rely on a water tank for heat storage.

PASSIVE SOLAR SYSTEMS

A different approach to solar collection,storage and distribution can be seen in “pas-sive” solar systems (Figure 3). Rather thancollecting solar energy through roof-mountedpanels, passive systems allow sunlight to enter

the building directly through south-facingwindows or skylights. The interior walls andfloors act as absorbers, converting sunlight toheat. Walls and floors also function as storage,provided they have sufficient mass. Heat iscontained in the structure by insulating aroundthe outside of the ceilings, walls and floors.Within the building, heat is distributed prima-rily by natural convection and radiation, ratherthan by mechanical means.

There are many ways to design solarenergy systems, not all of which can be easilyclassified as strictly active or passive. Forexample, some homes rely on south-facingglass to collect solar energy but use fans andductwork to distribute the heat. These designsare often known as hybrids. In any case, eachtype of solar system can be desirable, depend-ing on your particular situation. The followingchapters will describe these systems in greaterdetail and illustrate their appropriate use.

Fig. 3: The NCSU Solar House with direct gain, trombe walls, sunspace, active solarwater heating system and photovoltaic electrical system.

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CHAPTER 3THE SUN AND A L ITTLE ENGINEERING HELP

Mechanical Power Makes“Active” Solar Systems More Efficient

Active solar systems basically are appliancesconsisting of solar collectors, a mechanicallypowered distribution system and a heat storageunit. Active solar systems can be used tocondition household air or to heat water. InNorth Carolina, we mostly use active solarsystems to heat our hot water.

SOLAR WATER HEATING SYSTEMS

Did you know that the average person usesbetween 15 and 20 gallons of hot water a day?At 8 cents to 13 cents per kilowatt hour forelectricity, an average family of four spendsbetween $400 and $500 a year to heat water.That figure probably will continue to rise eachyear as the cost for energy rises. Youcan cut your hot water costsby half with a properlysized solar waterheater.

There already are more than 25,000solar water heaters installed on North Carolinahomes and the number is growing daily.Dealers and installers of solar water heatingsystems can be found in almost every largecity, as well as in many small towns. The N.C.Solar Center also offers a referral service freeof charge to the public.

There are four basic types of solar waterheating systems sold in the state, althoughother designs may be available. These systemsshare three similarities: flat-plate collectors togather solar heat, one or two tanks to store hotwater, and associated plumbing with or with-out pumps to circulate the heat transfer fluidfrom the tank to the collectors and back again.

The crucial difference in these systemslies in their freeze protection methods. In a“draindown system” (Figure 5), potable waterfrom the home’s hot water tank is pumpeddirectly through the solar collectors, where itis heated by the sun and returned to the tank.Freeze protection is provided by valves thatautomatically open and drain the system whensensors detect freezing temperatures. Thewater usually is dumped down a sewer drain.

The valves close when the danger of freez-ing has passed and fresh water is reintro-

duced to the system. Solar collec-tors and piping in a draindown

system must be pitched sowater will drain auto-

matically, even in apower failure.

Cold Water In

Black-ChromedCopper AbsorberPlate

Manifold Tube

Aluminum Frame

Riser Tubes

Insulation

Low-IronTempered Glass

Hot WaterOut

Fig. 4: Cut-away drawing of a typical solar collector.

SUNBOOK 6

Draindown systems are classified as “openloop” because they are tied directly into thedomestic water supply. You should test thehardness of your water before installing anopen loop system. Mineral deposits or aciditycan ruin the collectors.

The second general type is a “drainback”system (Figure 6), so called because fluid inthe collector loop drains back into a solarstorage tank whenever the pump shuts off.A drainback system does not circulate house-hold water up to the collectors. Instead it usesa separate plumbing line filled with distilledwater or some other fluid to gather the sun’sheat. The heat is transferred to the householdwater supply by means of a heat exchanger—a coil of copper pipe that runs into and out ofthe water tank. A drainback system operates

Fig. 5: Draindown solar water heating system.

strictly on gravity—whenever the temperatureis near freezing, the pump shuts off and thetransfer fluid drains back into the solar storagetank. A drainback system lacks some of thecontrols of a draindown system and does nothave to be pressurized. However, it doeshave pitched collectors and piping like thedraindown system to allow the transfer fluid

to drain back into the tank. Drainback systemsare classified as “closed loop” because the heattransfer fluid is contained in a separate plumb-ing line rather than being tied into the domesticwater supply.

A closed loop system using an antifreezesolution represents the third basic type of solarwater heater available (Figure 7). The useof antifreeze allows the system to operatecontinuously throughout the winter months.Because they are toxic, antifreeze solutionsmust be separated from household water bya double-walled heat exchanger.

There are several antifreeze solutionsused as transfer fluids in solar water heatingsystems. Two of the most popular are a pro-pylene glycol/water mixture and silicone oils.Propylene glycol is far less expensive thansilicone oil and is more widely used. However,the propylene glycol mixture can becomeacidic when constantly exposed to high tem-peratures and should be checked and replacedevery few years to avoid corrosion. Siliconeoils are noncorrosive, but they have a very lowsurface tension. This means they can seepthrough the smallest cracks.

Fig. 6: Drainback solar water heating system.

Sensor

DifferentialController

Drainback Tank with Internal Heat Exchanger

Pump

Pump

Flat Plate Collector

Sensor

Hot WaterTank

Hot Water Out

Cold Water In

Flat Plate Collector

DifferentialController

Hot WaterTank

Cold Water In

Hot Water Out

Sensor

Sensor

DraindownValve

SUNBOOK 7

THE COLLECTOR PANEL

A crucial feature in all solar water heatingsystems is the collector panel. The collectorwill be exposed to the harshest elements ofnature and must be made of strong, well-assembled materials if it is to last for 20 yearsas claimed by most manufacturers. A good

that a steeper angle (latitude plus 10 degrees)is often recommended in Southern climatesbecause it enables the collection of more of thesun’s heat throughout the year. The optimumtilt for solar water heating collectors in ourregion is around 45 degrees. Collectors that tiltas much as 15 degrees off the optimum slopestill will perform relatively well on an annualbasis. This variation makes it possible tomount the panels flush with the roof foraesthetic reasons.

We still have not mentioned the fourthtype, the “passive” solar water heating systemdesigns—“thermosiphoning” and “batch.”These are available commercially and are alsopopular among do-it-yourselfers. Both areclassified as passive solar water heating sys-tems as they do not require pumps to operate.

quality collector generally has a metal frame,a single pane glass cover (double glazing isunnecessary in most Southern areas), and acopper absorber plate and tube assemblythrough which the heat transfer fluid is circu-lated. The collector should be well insulatedon both the back and the sides (Figure 4).

As with other solar systems, the bestorientation for a solar water heating collectoris due south—three to seven degrees west ofmagnetic south depending on where you are inthe state. However, solar water heating collec-tors can face up to 30 degrees east or west ofsouth without a significant deterioration ofperformance.

Traditional wisdom has held that theproper tilt for solar water heating collectorsis equal to the latitude of the location wherethe system is being installed. However, keepin mind that hot water consumption is oftengreater and incoming water temperatures arelower during the winter months. You will find

Fig. 7: Pressurized glycol solar water system.

A basic law of thermodynamics says thatwhen a fluid—such as air—is heated, it be-comes less dense and is then easily displacedby the relatively denser cold fluid. This iscalled thermosiphoning or convection.

In a thermosiphoning solar water heater(Figure 8), the storage tank is located at leasttwo feet above the collectors so the coolerliquid from the bottom of the tank will natu-

PhotovoltaicModule

Glycol Loop

Cold Water In

Hot Water Out

Hot WaterTankSide Arm

HeatExchanger

ExpansionTank

DC Pumps

Hot WaterTank

Hot Water Out

Cold Water In

Flat PlateCollector

Fig. 8: Thermosiphoning solar water system.

SUNBOOK 8

Also, it is usually the pipes leading to andfrom the insulated enclosure that freeze. Thus,it may make more sense to drain the collectorduring the winter in climates like North Caro-lina. Even with the system shut down forseveral months, the breadbox heater can saveconsiderable electricity that otherwise wouldbe required to heat water. Materials for abreadbox water heater usually run no morethan $500.

Commercial batch collectors arealso available. You usually will find themassembled, with instructions for interconnec-tion to the house water supply. A plumber ora homeowner with plumbing experience cancomplete the installation. These already as-sembled collectors use better materials thansimilar materials available at home supplystores. Materials include low-iron insulatingglass, selective surface coated tanks and aparabolic reflector. Commercial batch collec-tor systems also may offer warranties, such asguaranteed protection from freezing by virtueof their increased thermal performance. Costsfor commercial batch collectors will rangefrom two to four times the cost of homeowner-built systems (Figure 10).

ACTIVE SOLAR SPACE HEATING

Much of what you have just read about solarhot water systems can be applied to activespace heating systems. The main differencesbetween the two systems are size, complexityof installation and initial cost.

Where size and initial cost are concerned,consider the collector area needed for an

rally drop down into the collector and beheated. Warmer transfer fluid heated in thecollectors will rise up to the tank. The cyclecontinues as long as the sun is shining.

Thermosiphoning solar water heatersare popular in non-freezing climates wheredomestic water can be circulated directlythrough the collectors. In freezing climates,an antifreeze solution contained in a separateloop is normally used. The main advantages ofa thermosiphoning solar water heater is that itrequires no mechanical energy to operate. Thebiggest disadvantage is that it heats only aboutone-fifth the volume of water that a pumpedsystem does. Also, a thermosiphoning systemcan be hard to install because the water tankmust be installed above the collectors.

According to the results of a comparativestudy by New Shelter magazine, the most costeffective of all solar water heating systems isthe “batch” or “breadbox” water heater (Fig-ure 9). In a batch heater, the water storagetank also functions as the collector. The tanksare used as collectors by putting one or twowater tanks, painted black, in a well-insulatedbox or other enclosure. The south wall of thebox is made of clear glass or plastic and tiltedat the proper angle so the sun shines directlyon the tank and heats the “batch” of water.Freeze protection can be provided by addingan insulated cover to the enclosure, giving thesystem the appearance of a giant breadbox—hence, the name “breadbox solar waterheater.” However, some homeowners findthat the effort required to open and close theinsulated cover during the winter is tiresome.

Fig. 10: Integral collector storage system.Fig. 9: Breadbox batch solar water heater.

SUNBOOK 9

water. The transfer fluid absorbs heat inthe collectors and then flows through a heatexchanger inside the storage tank. When thehouse needs heat, the water in the storage tankis pumped directly through baseboard heatingcoils, a heat coil in a radiant floor slab orthrough another heat exchanger in the warmair duct of the home’s space heating system.You can also meet your hot water needs byusing solar-heated water in the storage tank.

Another form of thermal storage usesphase-change materials. Phase-change materi-als include eutectic—or glauber—salts andparaffin wax that actually change from a solidto a liquid between 70 degrees to 85 degrees,absorbing heat in the process. When thetemperature drops, heat is given off as theliquid returns to its solid form. Phase-changematerials store two to five times more heat perunit volume than water or rock, but they aremore expensive and difficult to find for sale.

Connecting an active space heatingsystem with a conventional forced air heatingsystem is simple. However, matching solarto a hydronic heating system can be tricky.Baseboard hydronic systems usually aredesigned to use water heated from 160 degreesto 180 degrees. Flat-plate solar collectorsproduce water heated to 140 degrees or less.

If you have a hydronic heatingsystems, consult a reputablesolar dealer to see if intercon-nection makes sense for you.

A number of designs haveevolved using solar collectorsto preheat air or water for heatpumps. Low-cost, low-perfor-mance collectors can be used inthese applications as heat pumpscannot tolerate high tempera-tures. The cost effectiveness andperformance of these systemshave been highly variable, socommercial availability currentlyis limited. However, as researchprogresses, the future is brightfor solar-assisted heat pumps.

active solar system. Collector size will dependon your heating needs and how much of theseneeds you expect solar energy to provide.Because of costs involved, most active solarspace heating systems are sized to provide75 percent or less of a home’s space heatingneeds. The rest is supplied by a conventionalbackup heating system or a wood stove. Anactive solar system sized to provide 50 percentto 75 percent of the space heating and hotwater needs of a well-insulated, 1,500-sq. ft.home in the Piedmont area is likely to runbetween $8,000 to $10,000 (Figure 11).

Active solar space heating systems circu-late either air or liquid through collectors togather heat. Regardless of the heat transfermedium, most solar space heating systemsstore heat for later use at night or duringovercast days. Systems that circulate air forheat transfer commonly use either a large rockbin, or air-cored floor or masonry wall for heatstorage. With the help of fans, hot air is pulledout of the collectors, into a duct system andthrough the heat storage unit before returningto the collectors. By sundown, the system hasstored enough heat to account for much ofyour heating requirements during the night.

Systems that use a liquid transfer mediumusually store solar heat in a large tank of

Fig. 11: Active solar space heating system.

SUNBOOK 10

CHAPTER 4PASSIVE SOLAR DESIGN

Nature and Common Sense—Add Up To Savings

Before the introduction of modern heatingand air conditioning, Americans relied heavilyon sun, shade and natural air movement forheating and cooling. Reliance on the naturalelements was reflected in the building materi-als, orientation and design of their houses.

In the Southwest, for example, NativeAmericans typically built their homes under theoverhang of a south-facing cliff where theywere bathed in sunlight in winter yet fullyshaded in summer (Figure 12). Walls weremade of thick adobe or stone that absorbed theheat of the winter sun and released it into thedwelling at night. Protected by the overhang insummer, the thick walls kept inside tempera-tures cool.

In the Deep South, cooling was the majorproblem. People responded by developingpassive design features such as wraparoundporches to shade windows, cupolas and tallceilings to allow hot air to rise above headlevel, and “dogtrot” floor plans that allowedfor effective cross ventilation.

Today the reliance on proper orientationis the trademark of the passive solar home.So is the use of special building materials anddesigns for heating and cooling. As the costof conventional fuels increases and peoplebecome more aware of their natural and builtenvironments, passive design is rising inpopularity in North Carolina. Passive energysystems can be incorporated into both newand existing homes. The same technologiesthat are used for passive heating are also usedfor passive cooling. However, the difficultyof renovating an existing home makes passivebetter suited to new construction. The follow-ing sections cover a variety of passive solarenergy systems that can be designed easily intonew homes, either alone or in combination.Passive retrofit ideas for existing homes willbe discussed in Chapter 6.

ORIENTATION , LANDSCAPING

AND WINDOW LAYOUT

Builders of any new home, regardless ofheating system, should follow basic passivedesign principles in orientation, landscapingand window layout. The added cost, if any,will be small, but the energy savings can besubstantial.

Ideally, one of the long sides of thebuilding should face due south to expose asmuch of the roof and southern wall as possibleto the winter sun. Moderate deviations offtrue south are acceptable and advantageousin some instances. For example, if you areseldom home during the day, orient the homeslightly west of south to allow more sunlight induring the afternoon. The opposite orientationwould be best for an office building that needsto start gathering solar heat in the early morn-ing hours.

Regardless of your heating needs,deviations of more than 30 degrees shouldbe avoided if at all possible. At a 30 degreedeviation, the percentage of solar heat willdrop by about 10 percent from that of truesouth. Over 30 degrees of deviation will resultin a sharp drop in the available solar heat.

Fig. 12: Adobe pueblo under cliff overhang.

SUNBOOK 11

Large deciduous trees can be excellentfor maintaining an energy efficient home.Deciduous trees shade the house in the sum-mer and expose it to the sun when they droptheir leaves in the fall. If you have deciduoustrees on your lot, locate your house where itwill be shaded in summer but open to sunlightin winter. The southeast and southwest cornersof the house are prime locations for trees.

Once you have decided how to locate thebuilding on the lot, you can begin designingthe structure. Locate most of the windows onthe south side of the house where they willpick up winter sunlight. The windows on othersides of the house, particularly the west side,should be kept to a minimum. Windows facingwest pick up virtually no direct sunlight inwinter, but can cause severe overheatingproblems in the summer when the afternoonsun lingers in the western sky. Windowsshould not be totally eliminated on any side ofthe house since they are needed for providingcross ventilation, balanced light and a meansof emergency escape.

With a house designed along these basicprinciples of “sun tempering,” you can get as

much as 30 percent of the winter heating loadfrom solar energy. Further design changesthat add thermal mass and solar windows canincrease the share of heating provided by thesun up to 80 percent and at the same time helpreduce the cost of air conditioning.

DIRECT GAIN SYSTEMS:EFFICIENT PASSIVE DESIGNS

Direct gain systems allow sunlight into ahome’s living area through large sections ofglass facing south (Figure 13). Direct gaincan be the most cost effective of all passivedesigns because the heat produced by sunlighthitting the walls, floors and other objects doesnot have to be transferred to another part ofthe house.

However, the surface area of south-facingwindows and the capacity of your storage areashould be balanced. If the windows collectmore heat than the floor or walls can absorb,overheating occurs. Be sure you have at leastfive square feet of four-inch-thick mass forevery square foot of glass and you will haveenough capacity for storing the sun’s heat foruse later at night.

Fig. 13: Cut-away drawing of a direct gain passive solar house.

Quarry Tile

4" Thick Concrete Slab

Split-face Blockor Brick Wall

Double-paneInsulated Glass

Night-time Insulation

SUNBOOK 12

Building materials used in conventionalhome interiors—for example, wood andsheetrock—retain some heat. But their heat-storing capacity is limited. Masonry and waterare much better at storing heat. Masonry, ofcourse, can be used in interior walls and floorsof buildings. Water and phase-change materialsare normally contained in tubes arranged alongthe back wall of the living space or along theinside of the window. Storage materials shouldbe put where they receive direct sunlightduring the day. Materials out of direct sunlightsave only one-fourth as much heat as materialshit by the sun directly.

When the sun begins to set and insidetemperatures drop, the heat absorbed by thesematerials will radiate back into the room,moving as heat always does from a warmerto a cooler space. Properly designed thermalstorage materials should keep inside tempera-tures from fluctuating by no more than 13degrees over a 24-hour period.

While storage materials help maintaincomfortable air temperatures in most of thehouse, an uninsulated glass wall loses a lotof heat at night and will make one side ofthe house markedly cooler than the rest.You can greatly reduce this problem bycovering the windows at night with accor-dion insulating blinds or insulated drapes.Other approaches you can take to reducenighttime heat loss are exterior or interiorinsulated shutters or quilted roman shades.

With direct gain systems, the thermalstorage mass tends to be thinner and morewidely distributed in the living space thanwith other passive systems. This allows aneven distribution of heat throughout theroom or rooms, but requires some thoughtabout how the living space will be used.Do not cover the thermal storage areawith carpet or other materials that reducestorage capacity. Select and arrangefurnishings carefully so they do not interferewith solar collection, storage and distribu-tion. Another thought to keep in mind—sunlight fades different types of materials.

INDIRECT GAIN SYSTEMS

Some problems of direct gain systems oftencan be solved by using indirect methods ofsolar heating. As the name implies, indirectgain systems do not admit sunlight directly intothe living area. Instead, south-facing glass isplaced in front of a massive wall that absorbs,stores and transfers heat into the house.

One of the most commonly usedindirect gain systems is the Trombé wall(Figure 14), named after its inventor, Frenchscientist Felix Trombé. A Trombé wall usuallyis built of solid masonry—concrete, solid blockor brick—and painted black or covered with aselective coating on the outside to absorb andtransfer much of the heat to the living quarters.A sheet of glass or plastic covers the outsideof the wall to trap additional heat.

Heat is distributed from the Trombé wallto the house in two ways. During the day, airtrapped between the wall and the glass gathersheat and enters the room through vents at thetop. Cool household air is drawn between thewall and glass through floor-level vents, where

Fig. 14: Indirect passive solar Trombé wall.

Double-paneInsulated Glass

Block Wall

Outlet Vent

Inlet Vent

SUNBOOK 13

the cycle repeats itself as long as sunlightstrikes the wall. Heat also is gradually con-ducted through the Trombé wall and reachesthe living area near the end of the day. In a 12-inch wall, heat travels from between the walland glass to the living area in about eight hours.

The cycle plays nicely to your advantage.Sunlight striking a living room Trombé wallbetween 10 a.m. and 3 p.m. is released insideas heat between 6 p.m. and 11 p.m. In abedroom, you probably would prefer a 16-inchwall with an 11-hour heat-release cycle.

To prevent nighttime heat loss, you mustclose the vents along the Trombé wall aftersunset—usually by hand. Solar designers havefound many of us often forget about the vents,wasting the heat that is stored along the wall.You can avoid the problem by building theTrombé wall without vents as long as the airspace between the glass and masonry is ventedor shaded in the summer. If daytime heat isneeded in the adjacent room, windows incor-porated into the wall will help heat the room.An added benefit of a sealed Trombé wall isthat household dust cannot get into the spacebetween the wall and glass. Moveable insula-tion or double glazing also is advisable forTrombé walls.

WATER AS THERMAL STORAGE

As mentioned, water also functions wellas a thermal storage material. Somepassive solar designs substitute water-filled containers for the masonry wall.Water stores twice as much heat as anequal volume of concrete or brick.Water’s heat storing capacity allowsthe storage mass to be concentrated ina smaller area. Water responds morequickly to temperature fluctuations,which means that it will heat up earlierin the day but also cool off quicker atnight. Thus the glass in front of waterwalls must be covered with insulationat night to prevent excessive heat loss.

I SOLATED GAIN SYSTEMS

Unlike direct and indirect gain systems, iso-lated gain passive designs capture solar radia-tion in an area thermally separated from theliving space. Isolated gain systems allow forthe collection and storage components tofunction somewhat independently of the houseitself, while heat can be drawn from them asneeded. The sunspace or solarium is the mostcommon type of isolated gain system (Figure15). In Chapter 6, the attached greenhouse isdiscussed as an effective, low-cost option forexisting homes. However, the sunspace hasmuch greater flexibility in terms of design andperformance when incorporated into plans fora new home.

Isolated gain systems, such as the sun-space, collect solar radiation directly througha south-facing wall of glass. Heat then istransferred into the house as needed throughvents, doors or windows. In some sunspacedesigns, the back wall is made of solid ma-sonry to store and transfer heat for use duringnighttime hours. In this respect, the sunspaceis simply an expanded Trombé wall system.Instead of the glass being a few inches in frontof the wall, it is several yards away.

Double-paneInsulated Glass

Awning Windowsfor Ventilation

Quarry Tile

4" ThickConcrete Slab

Brick WallWindowsfor HeatTransfer

Fig. 15: Isolated passive solar attached greenhouse.

SUNBOOK 14

There are several other options thatcan improve the efficiency of a sunspace innew home construction. The sunspace can bedesigned into the house so the south glass wallis flush with the rest of the structure, eliminat-ing heat loss through the sides of the sunspace.On the other hand, temperatures inside isolatedsunspaces fluctuate more than in the rest of thehouse since no heating or cooling is provided.In this sense, sunspaces are considered semi-conditioned.

THERMAL ENVELOPE HOUSE

One variation in passive solar design is the“thermal envelope” or double shell house.The thermal envelope design combines theaccepted idea of a south-facing greenhousefor solar collection with the novel concept of acontinuous double wall around the roof, floorand north side of the house. During the winter,sunlight warms the air in the greenhouse andcauses it to rise. Vents at the top of the green-house allow heated air into the cavity betweenthe double-walled roof. The air travels to theback of the roof, down the north wall as itcools, under the house and back into thegreenhouse again in a continuous convectiveloop. Theoretically, this action creates a bufferzone of moderately warm air surrounding thehouse on four of its six sides, cutting heat lossto a minimum. Excess heat from the green-house also flows directly into the living areathrough open doors or windows.

Promoters of the thermal envelope designclaim they will provide 100 percent of thehome’s space heating needs. Test studies bythe Brookhaven National Laboratory donesome time ago indicated that thermal envelopehomes are highly energy efficient, but somebackup heat is usually required to maintaincomfortable temperatures through the winter.

There are a number of other potentialproblems with some of these designs. Theair cavities between wood stud walls mayincrease the risk of fire hazard. The doublewall design is more expensive than a singlewall design with extra insulation. Finally, if

the cavity under the house is not properlysealed, it may introduce unacceptable levelsof moisture into the house. Successful thermalenvelope houses are being built, but there areother ways of taking advantage of convectionloops inside the home for distributing heat.

HYBRID SOLAR SYSTEMS

The best solar system for a new home in termsof cost, comfort and convenience may wellbe a combination of both active and passivedesign, known as a “hybrid solar system.” Acombination may be as simple as adding a fanand ductwork to move hot air from a solariumto other parts of the house, or it could involvethe use of a number of separate systems. Forexample, daytime heat could be providedpassively by south-facing windows while anactive system is relied upon to heat the houseat night. An active system used only for night-time heating can be smaller and less expensivethan a system designed to provide all thehome’s space heating needs.

EARTH -SHELTERED HOMES

Some advocates of solar heating believe themarriage of passive solar and earth-shelteringcan result in the ideal home from an energyefficiency standpoint. An earth-shelteredhome is either built partially underground orbanked—bermed—with earth on one or moresides (Figure 16). Earth sheltering offers twomain advantages. One, cold air is not as likelyto leak inside. Also, the walls of the home arenot exposed to the same temperature extremesas conventional dwellings.

The deeper into the earth a house is built,the more stable the temperature. At two feetdeep in Raleigh, temperatures will vary from47 degrees in February to around 77 degreesin August. At 10 feet deep, temperatures runfrom 56 degrees in February to 68 degrees inAugust. While ground temperatures are moremoderate than corresponding air temperatures,insulation still is required to prevent excessiveheat loss and potential moisture problems fromcondensation on cold masonry.

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Whether earth-sheltered constructionis possible depends on site conditions andwhether financing is available for this formof housing. Earth-sheltered construction alsodepends on the familiarity of local contractorsand code officials with underground buildingpractices and whether this type of constructionis available in your area.

The ideal location for an undergroundhome is on a south-facing slope. The north,east and west walls can be set into the hillsidewhile the south wall is left exposed for passivesolar heating. Most underground houses areconstructed of 8-inch to 12-inch reinforced

concrete walls, which serve as excellentstorage for solar radiation collected throughsouth-facing glass. There is no reason whya well-insulated underground home with asouthern exposure cannot be 90 percent self-sufficient in heating and cooling.

Proper drainage and waterproofing alsoare important in earth-sheltered construction,so avoid low-lying sites. All surfaces exposedto the earth will require special waterproofing.Construction should be done correctly the firsttime to avoid costly expenses that might berequired later to repair leaks.

Fig. 16: Earth-bermed passive solar house.

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CHAPTER 5PASSIVE COOLING TECHNIQUES

Tips To Reduce Use Of Air Conditioning

In North Carolina, your air conditioning billcan run higher than your winter heating costs.But you can get summer relief from highenergy bills with passive cooling techniques.These techniques will not render your airconditioning unit obsolete. You would stillhave humidity problems without it. However,solar cooling can reduce significantly theamount of air conditioning you need.

In the hot, humid summers of the South-east, passive cooling involves a twofold ap-proach. First, direct sunlight must be keptout of your home as much as possible. South-facing windows and mass walls can be shadedwith extended roof overhangs (Figure 17)or other forms of shading. The length of theoverhang should equal roughly one-fourth thedistance from the bottom of the windowto the bottom of the overhang to shade thewindow in the middle of summer.

Because we have so many warm daysin late fall and early spring, it is impossible todesign a fixed overhang that ensures a com-fortable indoor temperature throughout theyear. Many homeowners prefer adjustableawnings for windows facing south (Figure 18).A trellis with vines or grapes is an attractive

and very effect method for shading but doesrequire maintenance. Interior blinds helpreduce heat buildup but are not as effective asshading that stops the sun before it hits thewindow glass.

Windows facing east and west cannot beprotected as easily from the rising and settingsun. These windows are best protected bydeciduous trees or solar window screens andfilms. If you have skylights, greenhouse roofglazing or other horizontal glass hit by the sunto worry about, you can still use sunscreens,vegetation or reflective shutters to cut downheat buildup. However, protecting skylightsfrom the sun is obviously more difficult thanshading your windows. If you’re building anew home, you must decide before construc-tion begins whether skylights are worth theextra expense in a passive cooling design.There are new solar light tubes on the marketthat can provide natural light without theexcessive heat build up.

Another approach to passive coolingincludes design features that promote aircirculation through natural convection. Ventsor windows built into the lowest and highestparts of your house will release hot air trappednear the ceiling while letting in cooler air. Thegreater the temperature difference betweenthe air at the top and bottom, the better yourcirculation will be. Clerestory windows orcupolas are often used in solar houses toprovide high ventilation areas. Providing atleast two windows on separate walls in aroom will greatly improve cross ventilation.

Fig. 17: Fixed overhang. Fig. 18: Retractable awning. Fig. 19: Trellis with vines.

SUNBOOK 17

CHAPTER 6LOW-COST SOLAR HEATERS

A Small Investment Can Get YouStarted In The Right Direction

You may decide that you do not want tobuild a new solar home or buy a completesolar heating system for your current home orapartment. Instead, you may want to build orbuy a number of solar heating devices that heatindividual rooms during the day. “Dayheaters”usually do not store heat for nighttime use, butthey save energy and cost considerably lessthan solar systems with storage.

WINDOW BOX COLLECTOR

The most inexpensive type of dayheaterprobably is the “window box collector.” Thewindow box collector is a rectangular box witha black absorber plate and airflow channelsabove and below the plate. The box is sealedwith glass or plastic on its sun-facing side andinsulated on all other sides. Insulation also isplaced on the back side of the absorber plateto prevent condensation and heat loss fromthe top channel (Figure 20).

The window box heater operates on thethermosiphoning principle mentioned earlier.When the box is positioned at the proper anglein a south-facing window, sunlight will heatthe air in the top channel above the absorberplate and cause it to flow upward into thehouse. As the warm air flows out of the topvent, cooler air will be drawn into the lowerchannel and heated. The process continuesas long as the sun shines.

Because window box collectors areinexpensive, portable and easy to build, theyare popular with renters. However, they cutoff sunlight from a portion of the windows.The close proximity of the inlet and outletvents also means the air going out of the boxmay be drawn back into the lower channel.

At best, a window box heater can be expectedto help warm an average-sized room duringthe middle part of a sunny day.

THERMOSIPHONING AIR PANEL

A thermosiphoning air panel—called a TAP—is another low-cost solar collector that heatsair by natural convection. TAP collectors aremounted against the outside wall of a houseand are similar in function to a Trombe wall.A TAP basically consists of a sheet of glassmounted in a wooden frame with an air spaceand a corrugated aluminum sheet behind it.The aluminum absorber plate is painted blackto soak up sunlight better and convert it toheat. Behind the absorber plate is another airspace, where warm air rises and enters theroom through a vent near the top. As warmair leaves the collector, cool air is drawn inbehind it through a vent near the floor.

Several construction features make thethermosiphoning air panel far more effectivethan a window box collector. Because the airin the TAP travels behind the absorber platerather than in front, less heat will be lostthrough the glass cover. Having the inlet andoutlet vents at opposite ends also leads tobetter air flow than in a window box unit.

The TAP holds one other advantage.Unlike the window box, it does not close offan existing window. Nevertheless, keep in

Fig. 20: Window box solar collector.

SUNBOOK 18

mind that a TAP requires cutting two ventsinto the wall. Cutting vents into the wall maynot be possible if you live in rental housing.

Thermosiphoning air panels can bebought ready made or can be built from mate-rials available at most building supply houses.The materials can be purchased for a reason-able price.

ACTIVE SOLAR WALL COLLECTOR

You can improve the heat output of a solarcollector like a TAP by installing a blower orincreasing collector size. A thermostaticallycontrolled blower alone can increase hot aircirculation by 20 percent. The small cost ofelectricity will be offset by the increasedheating capacity. If you install a blower, use aseries of baffles to force air through a serpen-tine pattern through the collector (Figure 21).The twisting path of the air will increase theamount of heat taken off the back of theheated absorber plate.

You also can increase the output of asolar air collector by increasing its size. A wallcollector can be built almost any size or shapeas long as you have the space for it. Ware-houses, farm buildings and other structures

with long, unbroken wall areas are excellentfor large wall collectors. On a sunny day, an 8foot by 8 foot collector will heat a 600 squarefoot area with about 60,000 BTUs.

Regardless of whether you build an activeor thermosiphoning collector, make provisionsto shade or vent it in the summer; otherwise,temperatures easily can rise to 150 degrees.Such high temperatures can warp and damagethe collector within a year.

ADDITIONAL WINDOWS

Adding windows to the south side of the housecan be one of the most cost effective waysto add solar heat to your home (Figure 22).Windows are very effective because sunlightcan enter the house directly to add to yourwarmth and comfort. A window offers littlecontrol but it is effective.

Make sure that the windows you addhave at least double-pane, insulated glass. Lowemissivity glass, which has a thin metallic filmthat blocks heat loss, is beneficial if you don'thave insulated shutters or curtains that sealtight against the window frame.

As mentioned in Chapter 4, windows thatexceed 7 percent of the floor space should beaccompanied by some kind of thermal storage.

ATTACHED SUNSPACE

The “attached sunspace” is a very popularsolar addition. The exact design may vary, buta sunspace serves as additional living spacewhile collecting the sun’s energy. A “green-house” also will collect solar heat while serv-Fig. 21: Active solar wall panel collector.

Fig. 22: Affordable passive solar home.

Upper Ventfor Warm Airto House

Lower Ventfor Cool Airfrom House

Blower

Plywood

Rigid Insulation

Absorber Plate

Single PaneGlazing Serpentine

Baffle Pattern

SUNBOOK 19

Fig. 23: Retrofitted attached solar greenhouse.

ing as an excellent place for growing plantsand vegetables (Figure 23).

You should weigh carefully whetheryou want a greenhouse or sunspace insteadof some other type of solar collector. If youmostly want a simple, cost effective strategy tocut your heating bill, a south-facing windowwith night insulation—or a wall collector—willbe preferable to a sunspace. On the other hand,if you want extra floor space and a higherpercentage of heat provided by the sun, thena sunspace may be ideal. If it is a greenhouseyou want, keep in mind that although they canprovide some heat to the house, a greenhousewill use the majority of the heat it produces tokeep its plants warm at night.

For the best wintertime collection, thesouth wall of a greenhouse should be totallyglazed and tilted about 55 degrees to 60degrees from horizontal. The tilt is especially

important since plants need maximum expo-sure to the sun in winter. On the other hand,you can build a sunspace with the glassmounted vertically and still get 85 percent ofthe available solar heat. Vertical mounting hasseveral advantages. It is simple to install andmuch easier to waterproof than a slanted wall.Also, a vertical wall is easier to shade—animportant advantage in reducing heat gain inthe summer.

Depending on your home design, buildingan entirely new structure may not be neces-sary. A porch or carport on the south sideof the house can easily be converted into asunspace by enclosing the sides with slidingglass door panels or double pane windows.For more information on building a low costattached sunspace, you can find additionalinformation in factsheets printed by the N.C.Solar Center.

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CHAPTER 7PHOTOVOLTAICS FOR THE HOMEOWNER

Technological BreakthroughsBring Solar Cells Home

In the next few years, the potential for usingphotovoltaic—popularly known as PV—power systems at home will increase dramati-cally as technological breakthroughs continueon an almost monthly basis. Besides thetechnological advances, prices keep droppingas production methods improve and commer-cial applications increase. Already, there arehundreds of homes in North Carolina that usephotovoltaic systems as their principal sourceof electricity.

Photovoltaic systems are usually madeup of a photovoltaic array, controls, an in-verter and battery storage. The PV arraycontains the individual solar cells. Storagetypically is provided by a deep-cycle, 12-volt,lead-acid battery. The heart of the PV systemis made up of controls and an inverter thatconverts the direct current solar energy producedby the PV panels or batteries into alternatingcurrent electrical power that can be used byconventional homes and appliances. Thecontrols and inverters also are instrumentalin how batteries are charged and discharged.

There are two classifications for PVsystems—stand-alone systems and utility-interactive systems.

STAND-ALONE PV SYSTEMS

The stand-alone system operates independentlyof any power line hooked up to your home.There are two types of stand-alone systems.“Direct systems” use electrical power as it isgenerated but have no storage capacity,whereas “battery storage systems” have thecapacity to store electrical power generated bythe photovoltaic system. Stored electrical

power is then available when the sun is notshining.

The possibilities for stand-alone PVsystems are extensive. Current uses of stand-alone systems are anything from water pumpsand navigational signals to electrification ofremote homes and area lighting. PV systemsrequire no fuel other than the sun and have lowmaintenance costs. For developing countries,photovoltaics are an ideal source of power andover 200,000 homes already get their electric-ity through small PV systems.

In North Carolina, PV systems areavailable commercially for path lighting, fans,active solar water heating system pumps,electric fences, highway construction signsand call boxes.

UTILITY -INTERACTIVE SYSTEMS

Utility-interactive systems are connected tothe power line that the local power companyhas running into your house. A typical utility-interactive system may have PV solar moduleson the roof, like the Solar House at NorthCarolina State University. Because photovol-taic systems convert power the PV panelsproduce into alternating current, it is possibleto sell your utility company any surplus poweryou might generate. However, any returnsprobably would be very modest. Since NorthCarolina does not currently have a “net meter-ing” law that requires the utility company tobuy electricity you produce at the same ratethey sell, your utility company will buy yoursurplus electricity only at wholesale prices.You should not expect to make much moneyfrom wholesale prices.

If the market continues as it has, largePV systems will be built and owned by electricutilities and large corporations. As a result,homeowners will benefit as system costs dropand use becomes more widespread. Between1970 and 1995, the cost of PV modules fellfrom $100 to $5 per peak watt. Prices areexpected to continue to drop in the future toa more affordable $1 to $3 per peak watt.

SUNBOOK 21

CHAPTER 8CONSUMER TIPS

* With a resurgence of demand forsolar energy systems, new companies are oftenentering the solar marketplace. Most compa-nies offer high quality products and use dealersand contractors who provide good service andinstallation. But not all. Some companies dealin shoddy products, hire fast-talking sales staffand allow systems to be installed by untrainedcontractors. Just as you would with any majorpurchase, be alert to these possibilities fromthe moment you contact a sales person to theday the solar system is installed and working.

* One way to ensure that you get agood solar system is to deal with a local firmthat has been doing business in your area fora number of years. The fact that a companyis new does not make its service or productsinferior. However, there are operators whowill take advantage of your enthusiasm forsolar energy.

* To locate dealers of active solar sys-tems, check the telephone yellow pages under“Solar Energy Equipment.” Designers ofpassive systems can be found under the “Ar-chitects” listing. You also can get a list ofsolar energy equipment dealers and designersin your area from the N.C. Solar Center.

Sponsored by the Energy Division of theN.C. Department of Commerce in cooperationwith N.C. State University, the Solar Centeroffers solar energy programs and resourcereferrals in North Carolina. You can go to theSolar Center to get free design reviews, factsheets and other information on solar energy.The Solar Center periodically holds work-shops, seminars, conferences, home toursand exhibitions on solar energy technologies.Headquartered at the N.C. State University

Solar House, the Center encourages visits tothe facility and the use of its library and mediacenter. The Solar Center also maintains awebsite at http://www.ncsc.ncsu.edu thatcontains an online resource directory, bibliog-raphy and electronic versions of factsheets.Call the Solar Center at 1-800-33-NC SUN or919-515-3480 or by email at ncsun@ncsu.edu.

* Call at least two or three dealers toget estimates on different solar systems. Nevercommit to buy a solar system after hearingonly one sales pitch. Be skeptical if the dealertries to force a sale on you immediately. Aresponsible solar dealer will not want you toregret your decision to purchase a solar sys-tem. Always ask the contractor for names ofother customers and call them to ask abouttheir experiences with the company. If pos-sible, take a look at their installations—youdon’t have to be a solar expert to recognizepoor workmanship.

Fast, dependable service should beone of the biggest requirements in selectinga contractor. If you are concerned about thereputation of a solar company, call the Con-sumer Affairs Division of the AttorneyGeneral’s Office at 919-733-7741. They caninform you of any legal action or complaintsagainst that business.

* Before the contractor gives you anestimate, make sure he performs a detailedanalysis of the space heating and hot waterneeds of your particular household. Theestimate is crucial in determining the propercollection area and storage necessary forvarious percentages of solar space heating orhot water. The contractor should also analyzethe effect a less-than-optimum exposure to thesun will have on the system’s performance.

* Once the contractor has completedthe analysis of your house, ask for a writtenestimate that includes a breakdown of all laborand material costs. Also ask to see a copy ofthe system’s warranty. Warranties offered by

SUNBOOK 22

different solar manufacturers and contractorsvary considerably, so compare them carefully.

Basically, there are two types of warran-ties—full and limited. A full warranty is prefer-able because it provides the consumer with themost protection. Full warranties guarantee theproduct in normal use and cover componentrepairs and replacement at no extra cost to thecustomer.

A limited warranty provides coverageonly for certain parts or services. For example,a limited warranty may not cover the replace-ment of a pump or fan. If the part has to beordered, you also may be responsible for theshipping costs. A full warranty should coversuch expenses.

If the individual components on yoursystem are from different manufacturers, youshould have a warranty from each manufac-turer. These warranties should be backed bythe seller and the distributor as well as themanufacturer. Regardless of the type of war-ranty provided, it should be read carefully todetermine the actual coverage.

* A written contract covering all aspectsof the installation should be provided by yoursolar dealer. The starting and completion datesshould be in the service contract, along witha schedule for payment. Final payment shouldnot be made until the system is fully installedand has operated normally for several days.

* Your solar dealer and any subcontrac-tors doing the installation should certify thatthey have insurance coverage, includingworkmen's compensation, property damage

and personal liability. You should check withyour own insurance company to see if yourexisting policy will cover potential damagesto the system or the house. Make sure thecontractor has obtained the necessary buildingpermits and that the system will not violateany local or state building codes. If you needclarification of the building laws, contact theConsumer Affairs Hotline of the N.C. Depart-ment of Insurance at 1-800-662-7777.

* Once the system is installed, it shouldbe thoroughly tested by the contractor and, ifinstalled on a new home, checked by the localinspector. Water systems should be pressuretested for leaks. You also may want to have atemperature gauge installed so you can ob-serve its performance from time to time. Thechecks provide one sure way for you to knowthe system is working properly.

* Finally, the best way to guaranteethat you get your money's worth in the solarmarketplace is to know as much about thesubject as possible. Hopefully, this booklet hasgiven you a good introduction to the basictypes of solar heating, cooling and hot watersystems. Additional information can be ob-tained by contacting the Energy Division orreviewing solar literature available at librariesand bookstores. To assist you in your research,a bibliography follows this chapter. Afterresearching the basics of solar technology, youwill be better prepared to ask insightful ques-tions about the particular systems offered byvarious solar dealers.

SUNBOOK 23

RESOURCE ORGANIZATIONS

STATE ORGANIZATIONS

Brick Association of North CarolinaP. O. Box 13290Greensboro, NC 27415Phone: (919) 273-5566Fax: (919) 273-3463

The Brick Association supports the use ofpassive solar as a viable energy alternative. Itencourages the use of passive solar guidelinesfor builders and architects developed by thePassive Solar Industries Council and NationalRenewable Energy Laboratory.

Carolinas Concrete Masonry Association1 Centerview Drive, #112Greensboro, NC 27407Phone: (910) 852-2074Fax: (910) 299-7346

The CCMA supports the implementation ofpassive solar applications. It distributes passivesolar energy conserving house plans thatincorporate the use of mass for thermal energystorage.

Energy Division,N.C. Department of Commerce

430 North Salisbury StreetRaleigh, NC 27611Phone: (919) 733-2230 or1-800-622-7131 (toll-free in N. C.)Fax: (919) 733-2953

As North Carolina’s state energy office, theEnergy Division conducts seminars and work-shops, administers federal programs related toenergy conservation, renewable resources andemergency planning, and offers free publica-tions on a wide range of energy topics. TheEnergy Division has projects under way in theresidential, commercial, industrial, agricultural,institutional and transportation sectors.

Farmer’s Homes Administration4405 Bland RoadRaleigh, NC 27609Phone: (919) 790-2720

The FmHA provides financing for home buyersin low to middle income salary ranges, anddistributes a passive solar home plan. The planis available for a nominal charge through thestate office listed or your county FmHA office.

Advanced Energy909 Capability DriveRaleigh, NC 27606Phone: (919) 857-9000 or1-800-869-8001 (toll free in NC)Fax: (919) 832-2696

Advanced Energy is a private nonprofit corpo-ration established by the N.C. Utilities Com-mission to reduce electrical demand and peakloads through research, education, demonstra-tion, and commercialization of energy effi-ciency techniques. Funds are contributed byelectric utilities serving North Carolina. Ad-vanced Energy provides consulting, testing andtraining to utility, residential, commercial andindustrial customers.

North Carolina Solar CenterBox 7401North Carolina State UniversityRaleigh, NC 27695-7401Phone: (919) 515-3480 or1-800-33 NC SUN (toll-free in NC)Fax: (919) 515-5778

Sponsored by the Energy Division of theNorth Carolina Department of Commerce, incooperation with North Carolina State Univer-sity, the N.C. Solar Center serves as the leadstate organization for solar energy programsand resources in North Carolina.

SUNBOOK 24

Headquartered at the NCSU Solar House,a demonstration facility that is open daily andSundays for public tour, the Solar Centerconducts workshops for consumers and build-ing professionals, operates a toll-free hot linefor solar-related inquires, publishes and distrib-utes solar publications, operates a videotapelending service and reference library, providesdesign assistance, offers a referral service to anetwork of 250 professionals, and offers toursand educational materials for teachers andstudents.

North Carolina Solar Energy Association850 West Morgan StreetRaleigh, NC 27603Phone: (919) 832-7601Fax: (919) 832-3339

The principal nonprofit membership associa-tion working to advance the use of solarenergy in North Carolina. Publishes “CarolinaSun”, a quarterly newsletter/magazine cover-ing solar developments in the state. Holdsconferences and workshops periodically onsolar topics. Membership open to the public.NCSEA is the state chapter of the AmericanSolar Energy Society.

Research Triangle InstituteP.O. Box 121943040 Cornwalis RoadRTP, NC 27709Phone: (919) 541-6000

An independent contract research institutelocated in the center of North Carolina’sResearch Triangle Park. RTI conducts re-search for and provides technical services toclients in government, industry, and publicservice. Research projects include photovolta-ics, energy economics, biomass and alternativeenergy.

N.C. Cooperative Extension ServiceBox 7602North Carolina State University104 Ricks HallRaleigh, NC 27695-7602Phone: (919) 515-2811

The N.C. Cooperative Extension Serviceprovides educational opportunities to thecitizens of North Carolina through countyextension offices in each of the 100 countiesand the Cherokee Indian Reservation. TheCooperative Extension Service employsdemocratic techniques to involve local citizensin planning and implementing educationalprograms directed at contemporary issues.

Industrial Extension ServiceCollege of EngineeringBox 7902North Carolina State University1600 Research IVRaleigh, NC 27695-7902Phone: (919) 515-2358Fax: (919) 515-6159

The Industrial Extension Service, with a staffof more than 20 professionals, links business,industry, government and the engineeringprofession with the College of Engineering.The Industrial Extension Service focuses onbringing many of the engineering faculty andlaboratories to bear on industrial, economicand societal problems and opportunities.

NATIONAL ORGANIZATIONS

Alliance to Save Energy1725 K Street, NW, Suite 509Washington, DC 20006-1401Phone: (202) 857-0666Fax: (202) 331-9588

Alternative Energy Resources Organization25 S. Ewing, Suite 214Helena, MT 59601Phone: (406) 443-7272Fax: (406) 442-9120

SUNBOOK 25

American Biofuels Association1925 North Lynn Street, Suite 1050Arlington, VA 22209Phone: (703) 522-3392Fax: (703) 522-4193

American Council for An Energy EfficientEconomy

1001 Connecticut Avenue, NW, Suite 801Washington, DC 20002Phone: (202) 429-8873Fax: (202) 429-2248

American Hydrogen Association216 South Clark Avenue, Suite 103Tempe, AZ 85281Phone: (602) 921-0433Fax: (602) 967-6601

American Solar Energy Society, Inc.2400 Central AvenueUnit G-1Boulder, CO 80301Phone: (303) 443-3130Fax: (303) 443-3212

American Wind Energy Association122 C Street, NW, 4th FloorWashington, DC 20001Phone: (202) 383-2500Fax: (202) 383-2505

Center for Maximum Potential BuildingSystems

8604 F.M. 969Austin, TX 78724Phone: (512) 928-4786Fax: (512) 926-4418

Center for Renewable Energy &Sustainable Technology

1200 18th Street, NW, #900Washington, DC 20036Phone: (202) 530-2202Fax: (202) 887-0497E-mail: info@crest.org

Center for Resourceful Building TechnologyP.O. Box 3866Missoula, MT 59806Phone: (406) 549-7678Fax: (406) 549-4100

Critical Mass Energy ProjectPublic Citizen215 Pennsylvania Avenue, SEWashington, DC 20003Phone: (202) 546-4996Fax: (202) 547-7392

Energy Efficient Building Association1829 Portland AvenueMinneapolis, MN 55404Phone: (612) 871-0413Fax: (612) 871-9441

Electric Power Research InstituteCommunications Services DepartmentP.O. Box 10412Palo Alto, CA 94303Phone: (415) 855-2411Fax: (415) 855-2954

Enersol55 Middlesex Street, Suite 221Chelmsford, MA 01863Phone: (978) 251-1828Fax: (978) 251-5291

Florida Solar Energy Center1679 Clearlake RoadCocoa, FL 32922-5703Phone: (407) 638-1000Fax: (407) 638-1010

Healthy House Institute430 N. Sewell RoadBloomington, IN 47408Phone: (812) 332-5073Fax: (812) 332-5073

SUNBOOK 26

International Institute for EnergyConservation

750 First Street, NE, Suite 940Washington, DC 20002Phone: (202) 842-3388Fax: (202) 842-1565E-Mail: iiec@igc.apc.org

Interstate Renewable Energy CouncilP.O. Box 1156Latham, NY 12110-1156Phone: (617) 323-7377Fax: (617) 325-6738

National Association of Home BuildersResearch Center

400 Prince George’s BoulevardUpper Marlboro, MD 20772Phone: (301) 249-4000Toll-free: (800) 638-8556Fax: (301) 249-0305

National BioEnergy Industries Association122 C Street, NW, 4th FloorWashington, DC 20001Phone: (202) 383-2540Fax: (202) 383-2540

National Center for Appropriate TechnologyP.O. Box 3838Butte, MT 59702-3838Phone: (406) 494-4572Fax: (406) 494-2905

National Energy Foundation5160 Wiley Post Way, Suite 200Salt Lake City, UT 84116Phone: (801) 539-1406Fax: (801) 328-3381

National Hydropower Association122 C Street, NW, 4th FloorWashington, DC 20001Phone: (202) 383-2530Fax: (202) 383-2531

Northeast Sustainable Energy Association23 Ames StreetGreenfield, MA 01301Phone: (413) 774-6051Fax: (413) 774-6053

Passive Solar Industries Council1511 K Street, Suite 600Washington, DC 20005Phone: (202) 628-7400Fax: (202) 393-5043

Renew America1400 16th Street, NW, Suite 710Washington, DC 20036Phone: (202) 232-2252Fax: (202) 232-2617

Rocky Mountain Institute1739 Snowmass Creek RoadSnowmass, CO 81654-9199Phone: (303) 927-3128Fax: (303) 927-4178

Solar Box Cookers International1724 11th StreetSacramento, CA 95814Phone: (916) 444-6616Fax: (916) 447-8689E-mail: sbc@igc.apc.org

Solar Electric Light Fund1734 20th Street, NWWashington, DC 20001Phone: (202) 234-7265Fax: (202) 328-2555

Solar Energy Industries Association122 C Street, NW, 4th FloorWashington, DC 20001Phone: (202) 383-2600Fax: (202) 383-2670

Solar Energy InternationalP.O. Box 715Carbondale, CO 81623-0715Phone: (303) 963-8855Fax: (303) 963-8866

SUNBOOK 27

Solar Energy Research & Education Foundation122 C Street, NW, 4th FloorWashington, DC 20001Phone: (202) 383-2665Fax: (202) 383-2670

Solar Rating & Certification Corporationc/o FSEC, 1679 Clearlake RoadCocoa, FL 32922Phone: (617) 323-7377Fax: (617) 325-6738

Southface Energy Institute241 Pine StreetAtlanta, GA 30308Phone: (404) 872-3549Fax: (404) 872-5009

Sun Day Campaign315 Circle Avenue, #2Takoma Park, MD 20912Phone: (301) 270-2258Fax: (301) 891-2866

Union of Concerned Scientists26 Church StreetCambridge, MA 02238Phone: (617) 547-5552Fax: (617) 864-9405E-Mail: ucs@igc.apc.org

U.S. Export Council for Renewable Energy122 C Street, NW, 4th FloorWashington, DC 20001Phone: (202) 383-2550Fax: (202) 383-2555

World Resources Institute1709 New York Avenue, NW, Suite 700Washington, DC 20006Phone: (202) 638-6300Fax: (202) 638-0036

Worldwatch Institute1776 Massachusetts Avenue, NWWashington, DC 20036Phone: (202) 452-1999Fax: (202) 296-7365

FEDERAL GOVERNMENT

U.S. Department of EnergyAlternative Fuels Hotline:

(800) 423-1363Clean Cities Hotline:

(800) 224-8437Building Energy Standards Hotline:

(800) 270-2633

Energy Efficiency and Renewable EnergyClearinghouse

U.S. Department of EnergyP.O. Box 3048Merrifield, VA 22116Toll-free: (800) 523-2929

National Renewable Energy Laboratory1617 Cole BoulevardGolden, CO 80401Phone: (303) 275-3000Fax: (303) 275-4053

National Technical Information Service5285 Port Royal RoadSpringfield, VA 22161Phone: (703) 487-4780Fax: (703) 321-8547

Photovoltaic Design Assistance CenterP.O. Box 5800, Division 6218Sandia National LaboratoriesAlbuquerque, NM 87185Phone: (505) 844-8161Fax: (505) 844-6541

Solar Thermal Design Assistance CenterP.O. Box 5800Sandia National LaboratoriesAlbuquerque, NM 87185Phone: (505) 844-3077Fax: (505) 844-7786

SUNBOOK 28

BIBLIOGRAPHYGENERAL SOLAR

Assessment of Solar Energy Technologies.Dennis A. Andrejko, AIA, editor. Boulder,CO: American Solar Energy Society,1989.

Available from N.C. Solar Center for $8.00,this soft cover publication presents each solartechnology in depth.

Alternative Energy Sourcebook. JohnSchaeffer. Ukiah, CA: Real Goods Trad-ing Corporation, 1992.

Essentially an expanded catalog, this book hasexcellent chapters on resource efficient livingand renewable energy. Cost is $23 from RealGoods at 1-800-762-7325.

A Builder’s Guide to Energy Efficient Homesin North Carolina. Jeffrey S. Tiller &Dennis B. Creech. Raleigh, N.C.: N.C.Department of Commerce, Energy Divi-sion, 1992.

This book was written by Southface EnergyInstitute for the Energy Division and is agood manual on energy efficiency for thehomeowner and homebuilder. The cost is $7from the Energy Division at (919) 733-2230.

The Builder’s Guide to Solar Construction.Rick Schwolsky and James I. Williams.New York, NY: McGraw-Hill Book Co.,1982.

A practical guide to solar home constructionfor all. Many photographs and drawingsillustrate construction techniques.

Design with Nature. Ian L. McHarg. GardenCity, NY: Doubleday & Company, Inc.,1969.

A well-known book which deals with climaticdesign and site planning, particularly as itpertains to urban planning and development.

A Golden Thread. Ken Butti & John Perlin.Palo Alto, CA: Cheshire Books, 1980.

This is an entertaining and informative book onthe history and lore of solar energy.

More Other Homes and Garbage. Jim Leckie,Gil Masters, Harry Whitehouse, & LilyYoung. San Francisco, CA: Sierra ClubBooks, 1981.

Very useful for those looking to develop aself-sufficient lifestyle, it covers topics rangingfrom aquaculture to active solar collectors.$14.95 postpaid, (415) 923-5600.

Resource-Efficient Housing: an AnnotatedBibliography and Directory of HelpfulOrganizations. Robert Sardinsky.Snowmass, CO: Rocky Mountain Institute,1991.

This resource book will guide you to theorganization or information you need on arenewable energy topic. Order from RockyMountain Institute for $15.

Science Projects in Renewable Energy andEnergy Efficiency. NREL & DOE. Boul-der, CO: American Solar Energy Society,1991.

A great source for science projects in theclassroom or for science fairs. The materialis primarily short project outlines with somebackground information. Excellent bibliographyand resource guide. $10 from Solar Center.

PASSIVE SOLAR

Climatic Design. Donald Watson, FAIA andKenneth Labs. New York, NY: McGraw-Hill Book Company, 1983.

A well written guide to architectural consider-ations of passive solar design with many usefulformulae and indexes.

SUNBOOK 29

Designing & Building a Solar House. DonaldWatson. Pownal, VT: Garden Way Pub-lishing, 1985.

More conceptual than Climatic Design, thisbook is a complete guide to active and passivesolar energy in home design.

Design with Climate: Bioclimatic Approach toArchitectural Regionalism. Victor Olgyay.Princeton, NJ: Princeton University Press,1963.

One of the seminal works of passive solardesign. An excellent source of information forprofessionals and the general public.

Energy Conserving Site Design. E. GregoryMcPherson, editor. Washington, DC:American Society of Landscape Architects,1984.

Landscape Planning for Energy Conservation.Gary O. Robinette, editor. Reston, VA:Environmental Design Press, 1977.

The New Solar Home Book. Bruce Anderson.Andover, MA: Brick House PublishingCompany, 1987.

An updated version of a solar classic. Ander-son covers the basics of active and passivesolar design. $16.95 postpaid, from the N.C.Solar Center.

The Passive Solar Energy Book (ExpandedProfessional Edition). Edward Mazria.Emmaus, PA: Rodale Press, 1979.

No longer in print but worth looking for inyour local library. This is a very easy to useguide for designing passive solar homes.

Passive Solar Energy: The Homeowner’sGuide to Natural Heating and Cooling.Bruce Anderson and Malcolm Wells.Amherst, NH: Brick House PublishingCompany, 1994.

A well-illustrated and informative how-tobook which describes solar principles in simpleterms, with a minimum of technical jargon.

Passive Solar Retrofit Handbook. Thompson,Hancock, White Architects and Planners.Atlanta, GA: Southern Solar EnergyCenter, 1980. Available from N.C. SolarCenter for $8.

Sun, Wind, and Light: Architectural DesignStrategies. G.Z. Brown. New York, NY:John Wiley and Sons, 1985.

Written for architects, this book presents solardesign concepts for buildings and town plan-ning with many illustrations.

SOLAR HOUSE PLANS

Affordable Passive Solar Homes. Richard L.Crowther, FAIA. Denver, CO: SciTech,1984.

Many home designs by a well known solararchitect. Large and small, this is a good placeto start for the prospective home builder.Available from ASES for $20.

Energy Conserving House Plans. CarolinasConcrete Masonry Association. Greens-boro, NC: CCMA, 1983.

A copy of this planbook, which includes 18plans of 1,000-3,000 square feet in size, isavailable at no charge from CCMA.

Planbook for Low-Cost Energy EfficientHomes. Southface Energy Institute. At-lanta, GA: 1988.

This planbook includes five solar and energyefficient low-cost designs, each about 1,000square feet in size, and has been used byaffiliates of Habitat for Humanity in the con-struction of several of their homes. One copymay be obtained at no cost from SEI.

Solar Homes for North Carolina. N.C. Depart-ment of Commerce, Energy Division.Raleigh, NC, 1984.

A booklet containing 12 passive solar houseplans designed specifically for the NorthCarolina climate. Available at no cost fromthe North Carolina Solar Center.

SUNBOOK 30

Sun-Inspired Home Plans. Debbie Rucker,AIA. Greensboro, NC: Energetic Design,Inc., 1991.

This book includes four sets of designs, eachwith numerous options for changing size,facade, number of rooms, etc. It also containsan excellent section on energy considerationsfor those building their own home. To orderthis planbook, send $12 to: Energetic Design,P.O. Box 4446, Greensboro, NC 27404 (919)852-9131.

PHOTOVOLTAICS

A Guide to the Photovoltaic Revolution. PaulD. Maycock and Edward N. Stirewalt.Emmaus, PA: Rodale Press, 1985.

An introductory overview of the photovoltaicindustry and its impacts on society and theeconomy.

The New Solar Electric Home. Joel Davidson& Richard J. Komp. Ann Arbor, MI: AatecPublications, 1990.

One of the best overall books on photovoltaicsfor the homeowner with complete informationand many examples. $18.95 postpaid from theN.C. Solar Center.

Practical Photovoltaics: Electricity from SolarCells. Richard J. Komp. Ann Arbor, MI:Aatec Publications, 1995.

A recently-published guide to the practicalapplications of photovoltaics.

The Solar Electric House: Energy for theEnvironmentally-Responsive, Energy-Independent House. Steven Strong withWilliam G. Scheller. Emmaus, PA: RodalePress, 1993.

Written by one of the nations most knowledge-able photovoltaic designers, this book is awealth of practical information. Order fromthe N.C. Solar Center, $19.95.

The Solar Electric Independent Home. PaulJeffrey Fowler. Worthington, MA: FowlerSolar Electric, Inc., 1991.

A hands-on book with valuable details writtenfor electricians and homeowner, written by aphotovoltaic supplier, designer and installer.$17.95 postpaid from the N.C. Solar Center.

SOLAR WATER HEATERS

Active Solar Heating Systems Design Manual.Atlanta, GA: ASHRAE, 1988.

A technical evaluation of different systems andguide to systems sizing. Available fromASHRAE.

Active Solar Thermal Design Manual.Theodore D. Swanson, P.E., projectmanager. Baltimore, MD: Mueller Associ-ates, 1985.

A very technical manual on solar DHW systemsizing and design. Available from ASHRAE.

Design and Installation of Solar Heating andHot Water Systems. J.R. Williams.Woburn, MA: Butterworth Publishers,1983.

Installation Guidelines for Solar DHW Sys-tems in One & Two Family Dwellings.HUD-DOE Publication. Philadelphia, PA:Franklin Research Center, 1979.

Very useful and accessible nuts-and-boltsinformation on installing Solar DHW. Avail-able from N.C. Solar Center for $10.

Solar Water and Pool Heating Design andInstallation Manual, Florida Solar EnergyCenter, 1679 Clearlake Road, Cocoa, FL32922-5703, 1992.

An installation guide focused towards solarcontractors and plumbers, with good diagramsand descriptions of water heating systems andmaterials.

SUNBOOK 31

Solar Water Heater Handbook: A Guide toResidential Solar Water Heaters. R. Mont-gomery and J.H. Livingston, editors. NewYork, NY: John Wiley & Sons, 1986.

LOW-COST SOLAR HEATING DEVICES

The Food and Heat Producing Solar Green-house. Rick Fisher and Bill Yanda. SantaFe, NM: John Muir Publications, 1980.

Authoritative and friendly with all the how-to’sfor greenhouses and vegetable growing. $8from John Muir Publications, (505) 982-4078.

The Homeowner’s Complete Handbook forAdd-On Solar Greenhouses & Sunspaces.Andrew M. Shapiro. Emmaus, PA: RodalePress, 1985.

An excellent reference for do-it-yourselfbuilding. Focused more on actual constructiontechniques than the Muir book. ContactRodale Press at 1-800-441-7761 for ordering,$19.95.

Solar Air Collectors - A Design and Construc-tion Guide for Low-Cost Systems.Alamosa, CA: San Luis Valley SolarEnergy Association.

Solar Retrofit. Daniel K. Reif. Andover, MA:Brick House Publishing Company, 1981.

Includes descriptions and plans for retrofittinga direct gain system, solar greenhouse,thermosiphoning air panel, and active solarwall collector. Call (508) 635-9800 for order-ing, $11.95.

Solar Wall Collector Plans Review. DonMalloy and Ambrose Spencer.Brattleboro, VT: Northeast Solar EnergyAssociation, 1987.

A comprehensive source and evaluation ofwall collector plans. Good general informationon all styles and materials. Available fromNESEA, (413) 774-6051.

PERIODICALS

Carolina SunNorth Carolina Solar Energy Association850 W. Morgan St.Raleigh, NC 27603(919) 832-7601, Fax: (919) 832-3339

Free with membership in NCSEA. This maga-zine/ newsletter will keep you up to date onsolar and energy information and events.

Energy Design UpdateCutter Information Corporation37 BroadwayArlington, MA 021741-800-964-5118

$297 per year. $197 discounted price forcontractors and educators. A very thoroughreporting of national energy news relating tobuilding products and techniques.

Home Energy2124 Kittredge, Suite 95Berkeley, CA 94704(510) 524-5405

$49 for six issues. Geared toward energyprofessionals and contractors, this magazine isa reliable source for information, issues andconstruction techniques.

Home Power MagazineP.O. Box 520Ashland, OR 97520

$22.50 for six issues. The source for do-it-yourself information on all types of solarenergy with an emphasis on electric power.This magazine is informative and enjoyable.

Solar Industry Journal122 C Street, NW, 4th FloorWashington, DC 20001(202) 383-2600

$25/year, free to SEIA members.A trade journal for U.S. solar equipmentmanufacturers, installers and institutions, thisjournal covers current events world-wide.

SUNBOOK 32

Solar TodayAmerican Solar Energy Society2400 Central Avenue, Unit G-1Boulder, CO 80301(303) 443-3130

$29/year, free to ASES members. This broad-based current events magazine is an excellentsource for information on recent developmentsin all types of solar energy.

Sun WorldInternational Solar Energy Society192 Franklin RdBirmingham B30 2HE, UK+44 21 459 4826

$20/ 4 issues. Similar to Solar Today but withan international focus.

FACT SHEETS

These fact sheets are provided free of chargeby the North Carolina Solar Center. Call tollfree: 1-800-33-NC SUN, inside North Caro-lina, or (919) 515-3480 to request a copy ofthe following:

Cost of Photovoltaic-Generated Electricity

Decorating Your Passive Solar Home

Energy Education Resources for Teachers andStudents

Energy-Saving Landscaping for Your PassiveSolar Home

Heating Your Swimming Pool with SolarEnergy

Information Resources for Conservation andRenewable Energy

Low-Cost Solar Options for Retrofit andAffordable Housing

Passive and Active Solar Domestic Hot WaterSystems

Passive Cooling for Your North CarolinaHome

Passive Solar Design Checklist

Passive Solar Options for North CarolinaHomes

Passive Solar Retrofit for North CarolinaHomes

Photovoltaic Applications

Photovoltaic Power System of the NCSUSolar House

Photovoltaics: Electricity from the Sun

Selecting a Site for Your Passive Solar Home

Siting of Flat Plate Solar Thermal Collectorsand Photovoltaic Modules

Solar Energy and You

Solar Energy: An Overview

Sources of Solar Home Plans

Space Heating with Active Solar EnergySystems

Summer Shading and Exterior Insulation forNorth Carolina Windows

Sunspace Design Basics

Troubleshooting Your Solar DHW System

Tax Credit Guidelines

A Word to the Wise