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Ene 01 Energy efficiency

(all buildings)

Number of credits available Minimum standards
15 Yes

Aim

To recognise and encourage buildings that minimise their operational energy consumption through good design.

Assessment criteria

The following is required to demonstrate compliance for:

Up to 15 credits

Option 1 – Use of Approved Building Energy Calculation Software

  1. The energy performance of the building is calculated from design information using approved energy calculation (modelling) software and the number of credits achieved is based on the predicted energy performance of the assessed building compared to the performance of an equivalent Notional building (see CN6) designed to meet, but not improve on, the current building energy performance standard.
  2. The Energy Performance Ratio for International New Constructions (EPRINC) is calculated using BREEAM’s Ene 01 calculator, which takes account of the following parameters:

    1. The building’s operational energy demand
    2. The building’s primary energy consumption
    3. The total resulting CO2 emissions.
  3. The calculation is determined using the following data on the building’s specified/designed Service energy and fabric performance modelled using approved building energy calculation software:
    1. Building floor area (m2)
    2. Notional building energy demand (MJ/m2)
    3. Actual building energy demand (MJ/m2)
    4. Notional building primary energy consumption (kWh/m2)
    5. Actual building Primary energy consumption (kWh/m2)
    6. Notional building emission rate (kgCO2/m2)
    7. Actual building emission rate (kgCO2/m2).
  4. Modelling is carried out by a Suitably qualified energy modelling engineer and/or accredited expert who is responsible for verifying that the data entered in the energy model is appropriate.
  5. Compare the relevant EPRINC achieved with Table - 21 of benchmarks below and award the corresponding number of BREEAM credits.

Table - 21: Ene 01 EPRINC benchmark scale

BREEAM credits

EPRINC

Minimum requirements

1 0.06 To achieve one or more credits requires an improvement on the Notional building level as defined in CN6 Generating the notional building.
2 0.12
3 0.18
4 0.24
5 0.3
6 0.36 BREEAM Excellent requires a minimum EPRINC of 0.36 (6 credits).
7 0.42
8 0.48
9 0.54
10 0.6 BREEAM Outstanding requires a minimum EPRINC 0.6 (10 credits).
11 0.66
12 0.72
13 0.78
14 0.84
15 0.9 15 credits require a minimum EPRINC of 0.90 (15 credits) and Zero net carbon (CO2) emissions

A detailed description of how a building’s modelled operational energy performance and CO2 emissions are benchmarked against the above scale is provided in the ‘Calculation procedures’ within the Additional Information section.

Up to 10 credits

Option 2 – Energy efficient design features

  1. Where Option 1 is not available or feasible in the country of assessment, the energy performance of the building is determined using Option 2 Checklist A5.
  2. A building services engineer has confirmed Option 1 is unsuitable and has used Option 2 Checklist A5 to determine the number of credits available for this issue.
  3. The building services engineer has confirmed the items selected within the checklist are appropriate to the building type and local climatic conditions to award a maximum of 10 of the available credits.

Exemplary level criteria

The following outlines the exemplary level criteria to achieve innovation credits for this BREEAM issue:

Five credits

  1. The building has been modelled using Option 1 and the modelling demonstrates that the building is ‘Carbon negative building’ in terms of its total operational energy consumption (see Relevant definitions).

Up to four credits

  1. The building achieves 15 BREEAM credits under Option 1, i.e. zero net CO2 emissions (see Relevant definitions).
  2. The building has been modelled using Option 1 and the modelling demonstrates that an equivalent percentage of the buildings operational Service energy consumption, as stipulated in Table - 22, is generated by carbon neutral on-site, near-site or accredited external renewables and is used to meet Equipment energy demand from building systems or processes.

Table - 22: Innovation credit criteria for Ene 01

Innovation credits

Equivalent % criteria

4

80%

3 50%
2 20%
1 10%

Compliance notes

Ref

Terms

Description

CN1

Extensions to existing buildings

Where an existing building is being extended (and only the new extension is being assessed) and that extension uses existing building services plant, the energy modelling and percentage (%) improvement/reduction must be based on the building fabric of the new extension and any existing, common, building services plant and new building services plant installed that will service the new extension.

The energy modelling does not have to consider the existing building fabric where this will not form part of the scope of the BREEAM assessment. Nor does it have to consider existing building services where they are not supplying services (heating, cooling and/or ventilation) to the new extension being BREEAM assessed.

CN2

Shell only

When calculating the energy performance for a shell and core building, where heating, ventilation and air conditioning (HVAC) or lighting variables for the tenanted areas are not known, a developer is required to assume for the shell only spaces the most energy intensive fit-out specification permissible under local building regulations.

For the purposes of the BREEAM assessment it is permissible, when conducting the energy modelling, for the design team to substitute the fit-out performance specification (as defined in local building regulations when generating percentage (%) improvements for buildings with tenanted areas) for the performance specifications confirmed within a Green Lease Agreement, which are or will be legally committed to by the tenant(s). This rule applies only to those areas of the building that the scope of the green lease covers. Speculative areas of the assessed building development not covered by the scope of such a lease must assume a performance compliant with local building regulations, but no better.

The use of a Green Building Guide for tenants fit out (as defined in Appendix D) cannot be used to substitute a fit out specification compliant with local building regulations for the purpose of assessing BREEAM issue Ene 01, because this type of Guide is not legally enforceable, i.e. it is not a contract or lease condition.

CN3

Approved Building Energy Calculation Software

In countries with an existing National Calculation Methodology (NCM), the tool(s) approved for use under the NCM can be used as approved building energy calculation software. These will be confirmed by BRE as part of the the Approved standards and weightings list process.

Where the design team wishes to use an alternative modelling software package for the purposes of assessing this BREEAM issue, please refer to the Approved standards and weightings list to determine whether the modelling software package meets the minimum requirements in terms of:

  1. Minimum capabilities
  2. Design features
  3. Testing.

Where those minimum requirements are met, approval from BRE Global will be required (via the Approved standards and weightings list process) before the package can be used for the purposes of demonstrating compliance with Ene 01.

CN4

Suitably qualified energy modelling engineer and/or accredited expert

Where a National Calculation Methodology (NCM) requires accredited experts to undertake the energy performance calculations, these accredited professionals are also required to demonstrate compliance with this BREEAM issue.

If the NCM does not require accredited experts or alternative approved building energy calculation software is used, then a suitably qualified energy modelling engineer must carry out the modelling (see Relevant definitions).

CN5

Hierarchy of options

Option 1 must be used where available to design teams in the country of assessment. Where there is no operational National Calculation Methodology (NCM) in place OR where the NCM does not allow the design team to undertake an analysis of issues such as lighting or renewable energy generation, the design team may undertake a more thorough analysis of the performance of the building using alternative approved building energy calculation software.

Option 2 is available for design teams unable to carry out energy modelling of their building and where there is no operational National Calculation Methodology (NCM) in place. However, because energy modelling is the preferred way to demonstrate that a building is energy efficient, a maximum of 10 credits is available under Option 2.

CN6

Generating a notional building

The notional building will be generated using EITHER:

  1. Local building regulations or standards, OR
  2. Appendix G of ASHRAE Energy Standard 90.1-2010 (for all buildings except low rise residential buildings) or ASHRAE Energy Standard 90.2-2007 (for low rise residential buildings), OR
  3. A notional reference building as defined in the UK’s NCM. This option is only available where the building is located in a temperate climate (Köppen Geiger climatic zone Cfb).

Options 2 and 3 above are only available in countries where local regulation is less rigorous than Appendix G of ASHRAE Energy Standard 90.1-2010 or the UK’s NCM.

CN7

Determining the appropriate Ene 01 translator set

Please refer to the Approved standards and weightings list to determine the translator set for the country of assessment. If this has not yet been established for the country/region (i.e. this is the first BREEAM International 2013 assessment in the country), these translators will be allocated following completion of the weightings questionnaire.

Note: Where using options 2 or 3 above (CN6) the 'Good international practice' translator set must be used.

CN8

NCM output metrics

The three parameters assessed within this issue of demand, primary energy consumption and CO2 may not be recorded by the local National Calculation Methodology (NCM). Where this is the case, the relevant metrics to be assessed for this issue will be listed in the Approved Standards & Weightings List. If these are not defined for the country of assessment, contact the BRE for further guidance.

If the NCM does not provide figures for building emission rate (CO2) it will not be possible to demonstrate zero net carbon (CO2) emissions for the building and therefore a maximum of only 14 credits can be achieved.

CN9

Internal lighting not calculated using approved building energy calculation software

Where the chosen modelling/calculation tool accounts for the energy used for internal lighting, the maximum credits available for this BREEAM issue will be 15.

If internal lighting is not included within the modelling calculations, the credits available from modelling will be reduced and the remaining credits awarded for complying with the lighting criteria within Option 2 Checklist A5 checklist. Therefore:

  1. 12 credits will be available for residential buildings, with a further three available for compliance with the residential lighting criteria within Option 2 Checklist A5 checklist.
  2. 13 credits will be available for non-residential buildings with a further two available for compliance with the non-residential lighting criteria within Option 2 Checklist A5 checklist.

CN10

Renewable and low carbon Installations

Where included as part of the project (and therefore assessed under this BREEAM issue) the installation of low and zero carbon technologies can be used to improve the assessed building’s energy performance. The low and zero carbon (LZC) technology can be installed on-site or near-site where a Private wire arrangement is in place (see Relevant definitions) or off-site via accredited external renewables (see CN10 below).

CN11

Accredited external renewables

For the purpose of this BREEAM issue accredited external renewables are renewable energy schemes located off-site, but within the country in which the building is being assessed, which:

  1. Create new installed generation capacity, designed to meet the loads of the building (i.e. not just units of carbon).
  2. Are additional to capacity already required under pre-existing commitments.

At the time of writing, BRE Global are not aware of a mechanism for accrediting off-site renewables and consequently any renewable energy schemes that meet the above definition, although some Energy Service Companies (ESCOs) may achieve these criteria.

CN12

Energy exported to the grid Any electricity from an on-site LZC energy source that is exported to the grid may be included in the calculations as if it were used within the building.

CN13

Estimating energy demand from building systems/processes

At present BRE Global is not aware of a standard or national calculation methodology for modelling Equipment energy demands in a building. To demonstrate compliance with the ‘Exemplary level criteria’ the building’s modelled operational Service energy consumption is therefore used as a proxy for a building’s equipment energy demand. Whilst not accurate, this approach enables BREEAM to assess and award credits for buildings that meet a proportion of their equipment energy demand via carbon neutral on-site, near-site or ‘accredited external’ sources.

Where equipment energy demand for the building can be accurately predicted, possibly on the basis of metered data from the same or similar building type with the same equipment system/process loads, this data can be used to determine the percentage of equipment energy demand met via carbon neutral on-site, near-site or ‘accredited external’ sources.

Residential buildings only

CN14

Calculation procedure for multiple dwellings

The Ene 01 calculation should be completed for each dwelling and/or each energy type and/or each energy group (see Compliance notes CN14 and CN15). The energy performance ratio (EPRINC) should then be averaged for the whole development using the methodology within the Calculation procedures of the Additional information for either Option 1 or 2.

Where the advised averaging method is deemed unsuitable for the approved building energy methodology, a new calculation can be approved; please contact BRE for guidance. An example is where a NCM considers energy consumption in communal areas as well as per dwelling.

CN15

Energy type

A set of residences on a development are of the same ‘Energy Type’ if they have the same approved building energy calculation software output for performance data as outlined in criterion 3 of this issue. They will exhibit each of the following:

  1. Approximately the same size, built form and construction details.
  2. The same space heating, hot-water system and controls.
  3. The same orientation and level of over-shading/sheltering.
  4. The same assumed/actual air permeability and ventilation system.

CN16

Energy groups

Energy groups only apply when a building contains multiple flats/apartments within the same building envelope. The performance data outlined in criterion 3 of this issue can be averaged across the whole building provided that the same building services strategy is adopted throughout. These dwellings are defined as an energy group.

Note: This averaging rule cannot be applied to individual but adjoined housing and is subject to the following:

  1. Where varying servicing strategies (including the provision of renewable energy systems) are adopted in the building, dwellings should be grouped by strategy.
  2. Each energy group must be treated separately for the purposes of assessment and an average actual building emission rate and notional building emission rate is used to calculate the percentage improvement.

It is the BREEAM Assessor’s choice whether or not to use the energy groups averaging method or to complete calculation for each individual dwelling.

Non-residential buildings only

CN17

Energy modelling, BREEAM & building use/tenancy arrangement

The legislative criteria for energy modelling may vary according to building size, use, services and tenancy arrangement. In some instances modelling may be undertaken for the whole building; in others modelling may be undertaken for each individual unit or tenanted area within a building. The scope of a BREEAM assessment typically covers the whole building, regardless of whether that building consists of a number of units to be sublet.

Where energy modelling is required for each unit, for the purposes of determining the number of BREEAM credits, the EPRINC (as required for Option 1) is calculated as the area-weighted average EPRINC of each individual unit. Where the development contains conditioned shared and/or landlord spaces, the area of these spaces, unless otherwise accounted for, should be divided and attributed amongst the separate units. The proportion of shared areas attributed to each unit must be equivalent to the ratio of each unit’s area as a proportion of the total area of all units.

All units, heating systems and common areas within the assessed building must be accounted for in the assessment of Ene 01.

Schedule of evidence required

Ref Design stage
Post-construction stage
1-6

A copy of the report produced by the approved calculation tool for the assessed building at the design stage illustrating:

  1. The predicted actual building performance data and the Notional building performance data as listed in criterion 3.
  2. Name of the approved software used to carry out the modelling for calculating the energy performance.
  3. Confirmation of the expertise and experience of the individual carrying out the modelling in compliance with the requirements of the local building regulations.

AND

Where appropriate, a letter from the person carrying out the modelling confirming:

  1. Data used to model the notional building is taken from local building regulations, Appendix G of ASHRAE Energy Standard 90.1-2010 or the UK's National Calculation Methodology.

The output documents must be based on the 'As designed' stage of analysis.

Third party documentation, as follows:

  1. Actual building energy performance data from the standard output of accredited software, required as part of demonstrating the 'as-built' building complies with local building regulations, Appendix G of ASHRAE Energy Standard 90.1-2010 or the UK's National Calculation Methodology.
  2. 'As built’ drawings to demonstrate that the specification used and modelled at the design stage matches the specification of the completed building.
  3. Calculations associated with averaging, where it has occurred.

The final rating must account for any changes to the specification during construction.

7-9

A completed copy of the checklist.

Relevant specification clauses confirming details of compliance with each requirement.

Letter from the building services engineer confirming items selected from the checklist are appropriate to the building type and local climatic conditions.

'As built’ drawings and specification demonstrating compliance with the criteria.

10-12

A copy of a report, calculations/outputs from the manufacturer, supplier, engineer or software modelling confirming:

  1. The total carbon neutral energy generation (kWh/yr).
  2. The source of the carbon neutral energy.
  3. The calculated estimate of 'service energy’ consumption from systems/process (kWh/yr) (required only if confirming 'carbon negative' status).
  4. The calculated estimate of exported energy surplus (required only if confirming ‘Carbon negative building’ status).

As required for criteria 1-7 and at the design stage.

Additional information

Relevant definitions

Actual Building Emission Rate
This is the predicted building’s CO2 emission rate as designed expressed as kgCO2/m2/year and calculated in accordance with approved building energy calculation software.
Carbon negative building
A building/site that generates, surplus to its own energy demand, an excess of renewable or carbon neutral energy and exports that surplus via the national or local distribution grid to meet other, off-site energy demands, i.e. the building is a net exporter of zero carbon energy.
Surplus in this respect means the building/site generates more energy via renewable/carbon neutral sources that it needs to meet its own regulated and unregulated energy needs.
This definition of carbon negative focuses on only energy and carbon dioxide emissions resulting from the operational stage of the building life cycle (as this is the stated aim of this assessment issue). It does not take into account the embodied carbon, in terms of carbon fixing or emissions resulting from the manufacture or disposal of building materials and components (this is considered as part of BREEAM issue Mat 01 Life Cycle Impacts).
Carbon neutral building
Carbon neutral means that, through a transparent process of calculating emissions, reducing those emissions and offsetting residual emissions, net carbon emissions equal zero1Department for Energy and Climate Change, Oct 2009. See also, zero net CO2 emissions definition below.
Energy demand
The sum of the calculated annual demands for heating and cooling of the building, based on the relevant design details and subject to the standard weather conditions for the country of assessment. This is expressed in MJ per m2 of floor area and calculated in accordance with approved building energy calculation software.
Energy Performance Ratio for International New Constructions (EPRINC)
A metric that is unique to BREEAM and calculated by the BREEAM Ene 01 calculator tool (and the BREEAM Ene 01 Compliance Checker website) using outputs from the approved building energy calculation software. It is a ratio that defines the performance of a BREEAM assessed building in terms of its service energy demand, primary energy consumption and CO2emissions. This measure of performance is used to determine the number of Ene 01 credits a building achieves in the BREEAM assessment. A description of how the EPRINC is defined and calculated is provided in the Calculation procedures section of this issue.
Equipment energy
Building energy consumption resulting from systems or processes within the building, other than Service energy (see definition below). This may include energy consumption from systems integral to the building and its operation, e.g. lifts, escalators, refrigeration systems, ducted fume cupboards; or energy consumption from operational related equipment, e.g. servers, printers, computers, mobile fume cupboards, cooking and other appliances.
National Calculation Methodology (NCM)
A National Calculation Methodology (NCM) enables quantification of building operational energy consumption and CO2 emissions resulting from building services/systems and fabric performance. Within Europe, a country’s NCM is the methodology used for demonstrating compliance with the EU Energy Performance of Buildings Directive (Directive 2010/31/EU Of The European Parliament and of the Council of 19 May 2010 on the energy performance of buildings(recast).)
Near-site Low and Zero Carbon (LZC) Technologies
Renewable energy generated near to the site that is provided for all or part of the community, including the assessed building, e.g. decentralised energy generation linked to a community heat network or renewable connected via Private wire arrangement
Notional building
A hypothetical building of the same size and shape as the actual building, but with pre-defined specified properties for the building fabric, fittings and services.
Notional building emission rate
The notional building emission rate is the minimum energy performance requirement for a new building (kgCO2/m2/year) as defined by local building regulations. This is calculated in accordance with approved building energy calculation software and is expressed in terms of the mass of CO2 emitted per year per square metre of total useful floor are of the building (kgCO2/m2/year).
On-site Low and Zero Carbon (LZC) Technologies
Renewable energy generated on the site of the assessed development.
Primary energy consumption
This refers to the direct use at the source, or supply to users without transformation, of crude energy, that is, energy that has not been subjected to any conversion or transformation process2Glossary of Environment Statistics, Studies in Methods, Series F, No. 67, United Nations, New York, 1997.
Private wire arrangement
Where used in the context of BREEAM for low and zero carbon technology installations, a ‘private wire arrangement’ is defined as a system where any electricity generated on or in the vicinity of the site is fed directly to the building being assessed, by dedicated power distribution systems. If electricity is generated that is surplus to the instantaneous demand of the building, this electricity may be fed back to a national or local distribution grid. The carbon benefit associated with any electricity fed into the distribution network in this manner can only be allocated against an individual installation or building. In cases where a building is supplied by a communal installation, no carbon benefit can be allocated to buildings which are not connected to the communal installation. Similar assumptions and compliance rules should be applied to heat distribution systems.
Service energy
Building energy consumption resulting from fixed internal lighting systems, fixed heating or cooling, hot water service or mechanical ventilation.
Suitably qualified energy modelling engineer
A person with at least 3 year's relevant experience in energy modelling within the last 5 years and a recognised qualification such as a building services engineer or building energy modelling engineer. Their expertise should be broad enough to cover all required technical aspects, guaranteeing that the data entered in the energy model is appropriate and that the results reflect the actual performance of the building. It can be someone operating as a sole trader or employed by public or private enterprise bodies.
Zero net carbon (CO2) emissions
The net annual building CO2 emissions (kgCO2/m2/year) arising as a result of service energy consumption is equal to zero.
In aiming to achieve a zero carbon status, the building energy modelling can take account of contributions of energy generated from on-site, near-site and accredited external renewable and low carbon installations. Energy generated and supplied from off-site renewable and low carbon installations that are not accredited cannot be used to meet this definition.

Checklists and tables

None.

Calculation procedures

Ene 01 calculation methodology

A new calculation methodology for determining the number of credits achieved in the Ene 01 assessment issue has been introduced in to the BREEAM International New Construction 2013 version. This methodology is a departure from previous versions of BREEAM, which awarded credits based solely on a single carbon emissions metric. This change was made to enhance the ability of BREEAM to promote designs that minimise energy demand and consumption in buildings, and then to reduce the carbon emissions resulting from that energy use. The checklist approach has been maintained for use where this is not practical.

The new methodology considers three metrics of modelled building performance when determining the number of credits achieved for this issue, as follows:

  1. Energy demand: This measures how well the building reduces heating and cooling energy demand, it is influenced by factors including building fabric heat loss and air permeability.
  2. Primary energy consumption: This measures how efficiently a building meets its energy demand. It is influenced by factors including the type of building services systems specified and the efficiency of the energy generation and distribution infrastructure installed/utilised.
  3. CO2 emissions: This measures the amount of carbon dioxide emissions the building emits meeting its operational energy demands. It is influenced by factors including building fabric performance, systems and distribution efficiency and fuel source. The specification of low or zero carbon forms of energy generation (on site, near site or accredited external renewables) are accounted for in this parameter and they may also have a positive influence on primary energy consumption where they are displacing nationally supplied electricity or gas.

This triple metric approach ensures that standard practice against the energy efficiency or consumption scale cannot be completely offset by best practice against the carbon performance scale through the specification of low or zero carbon, on or off-site energy solutions. Therefore, BREEAM seeks to encourage and reward a holistic approach to reducing energy and CO2 emissions, through a balance of good building design and systems specification.

The procedure for translating performance in each of the above metrics into BREEAM credits is outlined in detail below along with a worked example. This includes a description of the BREEAM Ene 01 credits benchmark scale and how this relates to buildings and achieving net zero carbon status.

Approved building energy software will provide the necessary modelling data required to determine building performance. The design team will use this software to model energy performance and in some instances demonstrate compliance with local building regulations. This data is then entered into the BREEAM Ene 01 calculator to determine the Energy Performance Ratio EPRINC (a BREEAM International metric) and the number of credits achieved.

Stage 1 - Defining the building's performance improvement

Actual building performance, expressed as a percentage of the notional building level, is determined for the assessed building’s modelled energy demand, consumption and CO2 emissions.

Stage 2 - Benchmarking the performance improvement against the modelled building stock

Each of the percentages from stage 1 (demand, consumption and CO2 emissions) are then ‘translated’ into a ratio of performance expressed as a value between 0 and 1. See below for a detailed description of how the translators are derived and building performance is benchmarked.

Stage 3 - Weighting the individual ratios for each metric

The ratios from stage 2 are then multiplied by the weightings in Table - 23

Table - 23: Ene 01 Performance Indicator Weightings

Performance Indicator

Weighting

Energy demand

0.23

Primary energy consumption 0.38
CO2 emissions 0.39

This weighting reflects the maximum that each parameter can contribute towards the overall EPRINC and therefore BREEAM credits. See below for a description of the weightings and how they are defined.

Stage 4 - Awarding the BREEAM credits

The weighted ratios of performance from stage 3 are totalled to give an overall EPRINC which is then compared to the table of benchmarks and minimum standards to determine the number of BREEAM credits awarded. See below for a description of the BREEAM credits benchmark scale and its relation to international buildings and BREEAM’s minimum standards.

Translators

The Translators are derived and calibrated using actual building data, ensuring that a building’s performance is measured and compared against its peers. Actual building data is being collected from BREEAM assessments and therefore, until this country specific data is available, four generic translators representing varying national energy efficient building targets have been established. These will be:

  1. Best international practice in terms of energy efficient standards for buildings.
  2. Good international practice in terms of energy efficient standards for buildings.
  3. Robust energy efficient standards for buildings.
  4. Some energy efficient targets and standards for buildings.

The distribution curves are allocated to a country based on (i) a building’s potential to improve over regulations and (ii) standard industry practice in the country of assessment. Curves will be allocated for countries/regions based on a suitably qualified energy modelling engineers responses to a questionnaire (provided as part of the weightings questionnaire at the start of the project). The allocation will be applicable to all subsequent buildings being assessed within that country/region.

These distributions of performance are established for each metric of operational energy demand, primary energy consumption and total resulting CO2 emissions for a notional building. This distribution will then been used to define a means of benchmarking actual building performance (graphically represented by the curve in Figure 6 below).

Figure 6: Example Ene 01 building performance translator

Example Ene 01 building performance translator

The un-weighted ratio of performance for each metric is derived by determining the point that the assessed building's performance intersects with the translator curve. The weightings outlined above are then applied to the values calculated for each metric using this translation method. These weighted values are totalled to give the EPRINC, which is then used to determine the number of BREEAM credits achieved (outlined in stages 3 and 4 of the calculation procedure above). A completed example of this calculation procedure is provided in Ene 01 Energy efficiency.

Each metric translator curve is defined by best practice from the modelled building stock, and the following ‘policy’ decisions:

  1. Energy demand: A ratio of 0.80 will be achieved where the actual building achieves a defined level of typical best practice. Where typical best practice for demand is approximately a 25% improvement on the notional building (based on the correct distribution curve).
  2. Primary consumption: A ratio of 0.80 will be achieved where the actual building achieves a defined level of typical best practice. Where typical best practice for consumption is approximately an 18% improvement on the notional building (based on the correct distribution curve).
  3. Carbon dioxide emissions: A ratio of 0.60 will be achieved where the actual building achieves a defined level of typical best practice. Where typical best practice for CO2 emissions is approximately a 27% improvement on the notional building (based on the correct distribution curve).

The BREEAM EPRINC weightings

The weightings are intended to reflect the degree of influence that a designer has over the buildings performance against each metric. They also act to ensure that each metric is considered and building performance is improved before a high level of performance can be achieved in terms of BREEAM credits.

In terms of their derivation, the weightings are inversely proportional to the standard deviation of the translator curve(s). A metric with a larger standard deviation will therefore have a lower weighting. These weightings will be reviewed and fine-tuned over time as actual international building data is obtained through certified BREEAM assessments.

The weightings calculated based on inverse of the standard deviation for all four translators were compared. These were found to be very similar and so the weighting from the ‘good international practice’ data has been applied to all four translators (as opposed to having four sets of similar weightings for each set of international translators).

Future revisions to the translators, weightings and credit scale

The translators for this assessment issue are based on four generic distributions which represent varying national energy efficient building targets.

BRE Global will review and, where required, update these translators periodically as more country/region specific data becomes available via certified assessments and when building regulations are updated. This will ensure that BREEAM continues to align with achievable and cost effective best practice, whilst acting as a driver for low and zero carbon buildings.

Ene 01 Example Calculation

Table - 24: Example calculation for ‘good international practice’ distribution

Good International Practice Distribution curve data

Stage 1: Defining the building's performance improvement
Demand (MJ/m2) 94/145 = 0.648
Consumption (kWh/m2) 126/135 = 0.933
CO2 (kgCO2/m2) 28/33 = 0.848
Stage 2: Benchmarking the performance improvement against the modelled building stock, i.e. the point that a building's performance improvement intersects with the translator curve
Demand ratio 1 – (0.648 ^ 5.53) = 0.9090
Consumption ratio 1 – (0.933 ^ 8.10) = 0.4281
CO2 ratio 1 – (0.848 ^ 3.70) = 0.4555
Stage 3: Applying the weightings
Demand ratio 0.9090 x 0.23 = 0.2091
Consumption ratio 0.4281 x 0.38 = 0.1627
CO2 ratio 0.4555 x 0.39 = 0.1777
Stage 4: Determining the number of BREEAM credits
Overall EPRINC 0.2091 + 0.1627 + 0.1777 = 0.5495
No. of BREEAM credits 9 BREEAM credits (BREEAM Excellent)

Residential buildings only: Calculation for the whole development

Option 1 – Use of Approved Building Energy Calculation Software

The EPRINC calculation will need to be completed for each dwelling and/or energy type and/or energy group and the average weighted for the whole development. This can be achieved by:

Whole development EPRINC= TOTAL area of dwellings x [EPR (type 1)/Gross floor area (type 1) + EPR (type 2)/gross floor area (type 2) +.+ EPR (type x)/gross floor area (type x)]

Where the development contains conditioned shared and/or landlord spaces, the area of these spaces, unless otherwise accounted for, should be divided and attributed amongst the separate dwellings and/or energy types and/or energy groups. The proportion of shared areas attributed to each unit must be equivalent to the ratio of each unit’s area as a proportion of the total area of all units.

Option 2 – Energy efficient design features

The checklist will have to be completed for each dwelling and/or energy type and/or energy group. To award ‘x’ credits, the whole development must achieve the following:

  1. At least 80% of dwellings achieve ‘x’ credits.
  2. The remaining 20% of the dwellings achieve at least ’0.8x’ credits.

For example, where 80% of the dwellings achieve 6 BREEAM credits, the remaining 20% of the dwellings must achieve 0.8 x 6 = 5 BREEAM credits (4.8 rounded up) in order to award the higher amount, i.e. 6 BREEAM credits.

Other information

Whilst a number of energy/CO2 reduction strategies are not specifically named within BREEAM, this issue seeks to reward all energy/CO2 savings from techniques such as passive ventilation, ground water/night time cooling, cool roofs through the use of appropriate energy modelling methods. The assessor and design team should determine whether the selected modelling package adequately calculates the benefits of the technologies incorporated in the design.