HVAC Equipment HVAC Equipment Efficiency OverviewEfficiency Overview

Building Performance MattersBuilding Performance Matters

HVAC ComponentsHVAC Components

HVAC Components:HVAC Components:

1 Expansion valve

2 Fan

3 Compressor

4 Heat exchange coils

CondenserCondenser

HVAC Components:HVAC Components:

1 Heat exchange coils

2 Fan

1

2

Air HandlerAir Handler

HVAC Components:HVAC Components: Duct SystemDuct System

HVAC Components:

Supply DuctsSupply Ducts

Return GrilleReturn Grille

Return Return PlenumPlenum

Air Air HandlerHandler

SupplySupplyPlenuPlenumm

Duct SystemDuct System

S easonalE nergyE fficiencyR atio

Air Conditioner Efficiencies

Minimum SEER = 10 Btu’s/Whr for central home systems

Air Conditioner EfficienciesAir Conditioner Efficiencies

SEERs range from 10 to over 18 for very efficient AC units.

Going from SEER 10 to SEER 14 for example, will reduce cooling energy costs by about 30%.

Common Heating System TypesCommon Heating System Types

• Electric Strip

• Gas Furnace

• Heat pump

Common Heating System TypesCommon Heating System Types

• Electric Strip

• Uses either baseboard or air handler mounted electric resistance strips• Low installation cost but least efficient option.

Common Heating System TypesCommon Heating System Types

• Electric Strip

• Heat pump

• Air conditioner refrigeration cycle in reverse (heats home instead of cooling it).

• Cost effective vs. electric strip in all regions except very warm.

Common Heating System TypesCommon Heating System Types

• Electric Strip

• Gas Furnace

• Heat pump

• Similar efficiency to heat pumps

• Burns natural gas or liquid propane

Duct LeakageDuct Leakage

Duct LeakageDuct Leakage

0

1

2

3

4

5

6

7

8

9

10

Syste

m E

ER

0 5 10 15 20 25 30Percent Leak

Replaced Air = OutsideReplaced Air = Attic

Cooling System w/ Supply LeaksEffective System EER

Source:Contracting Business Apr94,Solving Leakage & Return Problems by

Duct LeakageDuct Leakage

HVAC-induced infiltrationHVAC-induced infiltration

Infiltration ratesInfiltration rates - - Florida Duct Florida Duct

Study 1990Study 1990

01020304050607080

Nu

mb

er

of

ho

uses

<0.25 0.25-0.5

0.5-0.75

0.75-1.0

1.0-1.5 1.5-2.0 >2.0

air change rate

Fan off Fan on

Duct LeakageDuct Leakage

Duct LeakageDuct Leakage

Florida 50 all electric

homes 13% total building

leakage in duct system

17% savings $200 cost

Duct Leakage Research 1990Duct Leakage Research 1990

Closing interior doors when AHU Closing interior doors when AHU fan onfan on

0.16

0.42

0.62

0.94

1.15

0

0.2

0.4

0.6

0.8

1

1.2

fan onfan off

Door ClosureDoor ClosureH

ou

se a

ir ch

an

ge

s p

er

ho

ur

(ach

)

Utility room door that swings to the return grill.

When the system turns on, the door is pulled to the grill, blocking air flow.

Duct Design ProblemsDuct Design Problems

SummarySummary

• Selecting efficient air conditioning based on your climate.

• Selecting the proper type of and efficiency heating system for your climate

• Designing and sealing air distribution systems properly.

HVAC efficiency includes: