Construction Studies An introduction to 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 required for: • New dwellings that apply for planning permission on/after 1 st. January 2007. • All existing buildings offered for sale or rent from 1 st. January 2009.
Primary Energy k. Wh/ m 2 per year Building standards & energy use Typical for Building Regs Part L 2005 Building Regulations 2007/08 Low/ Zero Carbon Irish construction standard/year
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 k. Wh/m 2/yr Kilo watt / hour 1 k. Wh of electricity costs 18 cent
Energy Labelling Domestic Appliances Energy labelling informs the consumer of costs.
What is Building Energy Rating? BER rating • Calculated using DEAP software. • DEAP – Dwelling Energy Assessment Procedure BER scale (k. Wh/m 2/yr) A 1, A 2, A 3, B 1, B 2, B 3 etc. CO 2 indicator (kg/m 2/yr)
Building Energy Rating (BER) Label • Each full band is 75 k. Wh/m 2/y and is indicated by a change of colour on the label. • Each small band is indicated by a change in the grade. Example: A 1 to A 2 to A 3 FULL BAND
Energy Costs and BER • Cost comparasions based on average energy costs for 2007 in a 250 m 2 dwelling
Current Building Regulations • A dwelling built to the 2007/08 building regulations should achieve a: • B or C rating
Building Energy Rating (BER) ? • 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
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 DEAP Computer Software Download from: http: //www. sei. ie/index. asp? doc. ID=1073
Information required for DEAP 45 individual inputs are needed to do a BER assessment on a dwelling on DEAP Energy used Dwelling Wall Heat Loss for light Reference Heat gains and losses Domestic Hot through Ventilation Water Details Construction type windows Living Area Roof Heat loss through Heated Loss Door heat loss to 21° Central Heating bridges thermal Details Floor Heat Loss
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 chimneys/flues Number of fans and vents 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 m 3/(h. m 2) for new dwellings @ 50 pa.
Information required for DEAP 4. Building elements (fabric heat losses) • Wall U-Value • Ceiling/Roof U-Value • Floor U-Value • Door & Window U-Values • Thermal bridging factor typical 0. 11 W/m 2 K
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. Level of Insulation on storage cylinder Insulation on pipe work. 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 Water heating • Solar photovoltaic • Geothermal energy • Wind power
Information required for DEAP 9. Lighting provision in the dwelling. • The percentage of energy efficient light fittings in the dwelling.
Information required for DEAP 10. Net space heat demand. • The heating requirements for the dwelling will depend on: • The total volume. • The living area %. Living area is assumed to be heated to 21 o. C and the rest of the dwelling heated to 18 o. C.
Information required for DEAP 11. Thermal mass category of the building ranging from: • Thermally light construction e. g. timber frame • Thermally massive construction. e. g. concrete block with hollowcore.
Energy rating worked example • Download the DEAP software from: http: //www. sei. ie/index. asp? doc. ID=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.
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