Construction Studies

An introduction to

Building Energy Rating

Building Energy Rating

Building Energy Rating (BER) grades the energy efficiency of a building

A Dwelling with a high rating will save the owner/ occupier money in energy costs.

Important dates for the BER

• New dwellings that apply for planning permission on/after 1st. January 2007.

BER required for:

• All existing buildings offered for sale or rent from 1st. January 2009.

Building standards & energy use

0

50

100

150

200

250

300

350

400

1972 1979 1982 1992 2002 Current Regs2010 ?

2016 ?Pri

mary

En

erg

y kW

h/

m2

per

year

Irish construction standard/year

Typical for Building Regs Part L 2005

Building Regulations2007/08

Low/ Zero Carbon

Main factors effecting BER

• Thermal insulation of the building

envelope.• Heat gains through glazed openings. • Ventilation and air permeability.• Domestic hot water system and control.• Space heating control and energy

required.• Lighting and internal heat gains.

What does BER measure?

• The BER measures energy use per square meter (floor area) of the dwelling per year.

• Measurement Unit

kWh/m2/yr

Kilo watt / hour1 kWh of electricity

costs 18 cent

Energy Labelling

Domestic Appliances

Energy labelling informs the consumer of costs.

What is Building Energy Rating?

• Calculated using DEAP software.

• DEAP – Dwelling Energy Assessment ProcedureBER scale (kWh/m2/yr) A1,A2,A3,B1,B2,B3 etc.

CO2 indicator (kg/m2/yr)

BER rating

Building Energy Rating (BER) Label

• Each full band is 75 kWh/m2/y and is indicated by a change of colour on the label.

• Each small band is indicated by a change in the grade. Example:A1 to A2 to A3

FULLBAND

Energy Costs and BER

• Cost comparasions based on average energy costs for 2007 in a 250m2

dwelling

Current Building Regulations

• A dwelling built to the 2007/08 building regulations should achieve a:

•B or C rating

• No obligatory minimum standard applies.

• BER must be produced by a registered BER Assessor.

• BER is valid for 10 years unless changes are made to the building.

• The BER is independant of how the occupants behave in the building.

• An advisory report must accompany a BER certificate

Building Energy Rating (BER) ?

Accompanying Advisory Report

•New build:To advise owners on how to use the features in the building to maximise energy efficiency

•Existing buildings:To advise owners on the options for upgrading of building to maximise its energy efficiency

Calculating the BER

Download from: http://www.sei.ie/index.asp?docID=1073

DEAP Computer Software

Property address Wall Area Low energy lighting %Wall U-value Living area %Door Area Thermal mass category

Planning reference number

Door U-value Heating controls# Chimneys Factor for thermal bridging Heat emitter# Permanent vents Window Area # Central heating pumps# flues Window Description Boiler interlock# fluleless gas fires Window Frame Material Space heating fuel# Sheltered sides Window OrientationDraught lobby Window OvershadingStructure type Water storage type 2nd space heating fuelDraughtstripping Water storage volumeVentilation method Insulation typeFloor Area Solar water heating

Floor U-valueRoof AreaRoof U-value Thermostat on cylinder

MPRN (electricity meter number)

Insulation on primary pipework

2nd space heating efficiency

Water heating system fuel

Water heating system efficiency

Main space heating system efficiency

Domestic Hot Water Details

Central Heating Details

Energy used for light

Floor Heat Loss

Roof Heat Loss

Wall Heat Loss

Dwelling

Reference

Ventilation

Information required for DEAP45 individual inputs are needed to do a BER assessment on a dwelling on DEAP

Door heat loss

Heat gains and losses through windowsConstruction type

Heat loss through thermal bridges

Living Area

Heated to 21°

Information required for DEAP

1. Dimensions:• The internal dimensions of the building

envelope.• New dwellings can be measured from the

plans.• Existing buildings may need to be surveyed.

Information required for DEAP

2. Ventilation Details

Number of fans and vents

Number of chimneys/flues

Number of sheltered sides

Presence of a draught lobby or porch.

Method of ventilation: Natural or Mechanical

Information required for DEAP

3. Air Permeability• Sealing of the building envelope.• Blower door testing required on

new dwellings.• Required to be 10 m3/(h.m2) for

new dwellings @ 50 pa.

• Ceiling/Roof U-Value

4. Building elements (fabric heat losses)

Information required for DEAP

• Wall U-Value

• Floor U-Value

• Door & Window U-Values

• Thermal bridging factor typical 0.11 W/m2K

Information required for DEAP

5. Glazed area heat losses and gains

• Glazed area sizes. • Orientation.

• Glazed unit U-Values - Glazing - Frame

• Solar transmittance.

Information required for DEAP

6. Details of the hot water system

Instant or storage system.

Insulation on pipe work.

Level of Insulation on storage cylinder

Temperature and time controls.

Information required for DEAP

7. Boiler and space heating details

Boiler efficiency %

Fuel used

Heating controls

Radiator’s or under floor heating

Information required for DEAP

7. Boiler and space heating details contd.

Insulation on pipe work.

Temperature and time controls.

Weather compensation controls.

Information required for DEAP

8. Renewable energy used, e.g.

• Solar photovoltaic

• Wind power

• Geothermal energy

• Solar Water heating

9. Lighting provision in the dwelling.

• The percentage of energy efficient light fittings in the dwelling.

Information required for DEAP

• The heating requirements for the dwelling will depend on:

Information required for DEAP

10. Net space heat demand.

Living area is assumed to be heated to 21oC and the rest of the dwelling heated to 18oC.

• The living area %.

• The total volume.

11. Thermal mass category of the building ranging from:

• Thermally massive construction. e.g. concrete block with hollowcore.

Information required for DEAP

• Thermally light construction e.g. timber frame

• Download the DEAP software from:

http://www.sei.ie/index.asp?docID=1073

• Install the software as per instructions.

• Use the software to do a sample rating on

the sample dwelling using the data

supplied.

• Vary the inputs to improve the rating.

Energy rating worked example