Further Guidance
- Scope of the DEAP
- Background to the DEAP
- General Principles
- Calculation procedures and conventions
- Standards and References
- BER Certificate
The Dwelling Energy Assessment Procedure (DEAP) is the Irish official method for calculating the energy performance of dwellings. The factors that contribute to annual energy usage and associated CO2 emissions for the provision of space heating, space cooling, water heating, ventilation, and lighting in DEAP include:
- Size, geometry, and exposure.
- Construction materials.
- Thermal insulation properties of the building fabric elements.
- Dwelling ventilation characteristics and ventilation equipment.
- Heating system(s) efficiency, responsiveness, and control characteristics.
- Cooling system efficiency.
- Hot water usage, system efficiency, storage, and distribution characteristics.
- Solar gains through glazed openings.
- Thermal storage (mass) capacity of the dwelling.
- Fuels used to provide space and water heating, space cooling, ventilation, and lighting.
- Renewable and alternative energy generation technologies.
The BER assessor should consider all aspects of the dwelling fabric and systems to reduce energy consumption and improve the BER result. The calculation uses standard assumptions regarding occupancy, levels and durations of heating, cooling, hot water demand, as well as usage of electricity for ventilation, pumps, and lighting. It is thus independent of the individual characteristics of the household occupying the dwelling when the rating is calculated, for example:
- Actual household size and composition
- Individual heating patterns and temperatures
- Ownership and efficiency of particular domestic electrical appliances
The procedure calculates and aggregates the monthly space heating energy balance for the October to May inclusive heating season. Where a fixed space cooling system is installed, DEAP calculates and aggregates the monthly space cooling energy balance for the cooling season (June, July, and August). DEAP then calculates the hot water energy demand based on dwelling size and various uses of hot water in the dwelling and accounts for heating system control, responsiveness and efficiency characteristics, fuel type and calculated lighting energy (electricity) requirement to determine the overall results.
A given dwelling specification will yield the same result in all parts of Ireland in respect of building regulations compliance and BER, that is independent of dwelling location. DEAP is based on the European Standard IS EN 13790: 2004 and draws heavily on the UK’s Standard Assessment Procedure (SAP).
Guidance in this guide must be followed by BER assessors when completing assessments.
The Building Regulations Part L (current and previous) can be found under gov.ie - Department of Housing, Local Government and Heritage (www.gov.ie).
The procedure and software may be used to generate BER labels and BER advisory reports as required under the EPBD and subsequent EPBD recast. This provision applies to new dwellings and existing dwellings as detailed in S.I. 243 of 2012. The format and content of the BER label is detailed here.
The energy rating ranges from G (largest primary energy usage) to A (lowest primary energy usage). It is critical to note that multiple factors including dwelling dimensions, orientation, ventilation, dwelling fabric, water heating, lighting, space heating, space cooling, heating controls and fuel type influence the building energy rating and must all be considered when determining the actual rating and where potential improvements could be made.
DEAP allows BER assessors to demonstrate a new dwelling’s conformance to certain sections of Building Regulations 2005 - 2022 TGD L. This Part L conformance checking does not apply to existing dwellings.
DEAP performs the following checks for new dwellings where Building Regulations 2005 TGD L applies:
- Building Regulations 2005 TGD L specifies that the DEAP methodology is used to show that the Carbon Dioxide Emission Rating (CDER) of the dwelling being assessed does not exceed that of a reference dwelling for which the corresponding Maximum Permitted Carbon Dioxide Emission Rate (MPCDER) is also calculated, both being expressed in units of kg CO2 per square metre per annum. The reference dwelling is specified in Appendix C of Building Regulations 2005 TGD L
- The overall heat loss method or elemental heat loss method, as defined in Section 1.2 of Building Regulations 2005 TGD L, should be satisfied.
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DEAP performs the following checks for new dwellings where Building Regulations 2008, 2011, 2019, 2021 and 2022 TGD L apply:
- The calculated primary energy usage of the proposed dwelling is divided by that of a reference dwelling, the result being called the Energy Performance Coefficient (EPC). DEAP compares the EPC to the Maximum Permitted Energy Performance Coefficient (MPEPC). The reference dwelling for this calculation is detailed in Appendix C of Building Regulations 2008, 2011, 2019, 2021 2022 TGD L. The MPEPC is defined in Section 1.1.2 of Building Regulations 2008, 2011, 2019, 2021, 2022 TGD L.
- The calculated CO2 emission rate is divided by that of a reference dwelling, the result being called the Carbon Performance Coefficient (CPC). DEAP compares the CPC to the Maximum Permitted Carbon Performance Coefficient (MPCPC). The reference dwelling for this calculation is detailed in Appendix C of Building Regulations 2008, 2011, 2019, 2021, 2022 TGD L. The MPCPC is defined in Section 1.1.2 of Building Regulations 2008, 2011, 2019, 2021and 2022 TGD L.
- The new dwelling must use a minimum level of renewable technologies (such as solar thermal systems, heat pumps, CHP, wood fuels and other small scale renewable systems). The amount of heat and/or electricity to be generated by these systems is defined in Section 1.2 of Building Regulations 2008, 2011, 2019, 2021 and 2022 TGD L. DEAP allows the renewables requirement to be met using either an individual, group, or district heating system. The energy contribution from renewables can also be specified using the ‘Renewables’ tab. In this case, the energy source must be specified as being a renewable technology (electrical or thermal energy) or a non-renewable technology.
- The ‘Renewables’ tab should not contain renewable or energy saving technologies already accounted for elsewhere in DEAP (such as heat pumps, biomass, solar water heating, CHP, and heat recovery). TGD L 2008 and 2011 define the renewable energy requirement as an absolute figure in kWh renewable energy per m2 floor area per year, whereas TGD L 2019, 2021 and 2022 define it as a renewable energy ratio (RER). DEAP automatically derives the renewable energy ratio for all different renewable technologies. Full detail of the DEAP algorithms including RER is available in the published Excel Workbook version of DEAP.
- The exposed elements of the dwelling fabric are required to meet the constraints detailed in Section 1.3 of Building Regulations 2008, 2011, 2019, 2021, 2022 TGD L. An average U-value must be met for each type of element. DEAP also checks that no individual section of an element exceeds the maximum U-value for that type of element. The calculation outlined in 1.3.2.3 of TGD L has also been added to the DEAP software. This calculation calculates the combined area weighted average U-value of all heat loss walls, roofs, and floors. According to 1.3.2.3 of TGD L, compliance can be achieved if this combined value does not exceed the combined area weighted average U-value of the heat loss walls, roofs and floors calculated with the U-values in Table 1, Column 2 of TGD L.
- As per Building Regulations 2008, 2011, 2019, 2021 and 2022 TGD L Section 1.3.1.2, the wall between a dwelling and an unheated unventilated space may not need to meet the U-value requirement for external walls. Please refer to the TGD L 2008, 2011, 2019, 2021 and 2022 for further guidance. DEAP allows BER assessors to exclude these walls from fabric U-value compliance checking under these circumstances. These walls are still considered to be heat loss walls, and an RU value should be applied to this semi-exposed heat loss wall by the BER assessor.
If an assessor is asked by a client to carry out a BER on a new dwelling where TGD L 2002 or earlier applies, they should notify the client that DEAP is not designed to carry out compliance checking to these earlier regulations. However, DEAP TGD L 2005 fabric insulation compliance checking can be used for elemental heat loss and overall heat loss method for TGD L 2002. TGD L 2002 and TGD L 2005 fabric insulation requirements are the same.
Compliance checking using the heat energy rating method should be calculated as per Section 1.4 of TGD L 2002, although the Assessor does not have a role in carrying out the heat energy rating.
BER assessors should also ensure that clients are made aware, in writing, of any non-conformance indicated in DEAP.