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Ene 04 Low carbon design

Number of credits available Minimum standards
3 No

Aim

To encourage the adoption of design measures, which reduce building energy consumption and associated carbon emissions and minimise reliance on active building services systems.

Assessment criteria

This issue is split into two parts:

The following is required to demonstrate compliance:

Passive design

One credit - Passive design analysis

  1. The first credit within issue Hea 04 Thermal comfort has been achieved to demonstrate the building design can deliver appropriate thermal comfort levels in occupied spaces.
  2. The project team carries out an analysis of the proposed building design/development to influence decisions made during Concept Design stage (RIBA Stage 2 or equivalent) and identify opportunities for the implementation of passive design solutions that reduce demands for energy consuming building services (see compliance note CN2).
  3. The building uses passive design measures to reduce the total heating, cooling, mechanical ventilation and lighting loads and energy consumption in line with the findings of the passive design analysis and the analysis demonstrates a meaningful reduction in the total energy demand as a result (see compliance note CN3.12).

One credit - Free cooling

  1. The passive design analysis credit is achieved.
  2. The passive design analysis carried out under criterion 2 includes an analysis of free cooling and identifies opportunities for the implementation of free cooling solutions.
  3. The building uses ANY of the free cooling strategies listed in compliance note CN3.1 to reduce the cooling energy demand, i.e. it does not use active cooling.

Low and zero carbon technologies

One credit - Low zero carbon feasibility study

  1. A feasibility study has been carried out by the completion of the Concept Design stage (RIBA Stage 2 or equivalent) by an energy specialist (see Relevant definitions) to establish the most appropriate recognised local (on-site or near-site) low or zero carbon (LZC) energy source(s) for the building/development (see compliance note CN3.3).
  2. A local LZC technology/technologies has/have been specified for the building/development in line with the recommendations of this feasibility study and this method of supply results in a meaningful reduction in regulated carbon dioxide (CO2) emissions (see compliance note CN3.12).

Checklists and tables

None.

Compliance notes

Ref

Terms

Description

Shell and core

CN1 

Applicable assessment criteria

Passive design analysis, criteria 1 to 3

Option 1 - Shell only: Criterion 1 - Hea 04 is not applicable to Shell Only assessments, however to achieve the Ene 04 Passive design credit, compliance with Hea 04 criteria 1, 2 and 3bii must be demonstrated.

 

Option 2 - Shell and core: All criteria relevant to the building type and function apply.

Free cooling, criteria 4 to 6

Option 1 - Shell only: All criteria relevant to the building type and function apply subject to the following: Only free cooling options 1 to 3 listed in compliance note CN3.1 are applicable. Option 2 - Shell and core: All criteria relevant to the building type and function apply.

LZC feasibility study, criteria 7 to 8

Option 1 - Shell only: All criteria relevant to the building type and function apply, subject to the following: Criterion 7: The LZC feasibility study must be completed as part of the shell only design, based on the expected building use and loads specified in the design brief or, where these are not specified, for likely scenarios. Criterion 8: The built form should allow for the future installation of the most cost effective LZC options. Option 2 - Shell and core: All criteria relevant to the building type and function apply.

Refer to Appendix D – BREEAM UK New Construction and Shell and Core Project Assessments for a more detailed description of the above shell and core assessment options.

Simple buildings

CN2

Applicable assessment criteria

All criteria relevant to the building type and function apply.

CN2.1 

Microgeneration technologies On-site LZC technologies are only eligible to contribute to meeting the criteria of this issue where the proposed solution can be classified as a microgeneration technology. The requirements for classification as a microgeneration technology must be met as described in compliance note CN3.5.
General

CN3 

Passive design analysis

See criterion 2.

As a minimum, the passive design analysis should cover:
  1. Site location
  2. Site weather
  3. Microclimate
  4. Building layout
  5. Building orientation
  6. Building form
  7. Building fabric
  8. Thermal mass or other fabric thermal storage
  9. Building occupancy type
  10. Daylighting strategy
  11. Ventilation strategy
  12. Adaptation to climate change.

CN3.1

Free cooling analysis

See criterion 6.

The free cooling analysis should demonstrate consideration of appropriate technologies from the following:
  1. Night time cooling (which could include the use of a high exposed thermal mass)
  2. Ground coupled air cooling
  3. Displacement ventilation (not linked to any active cooling system)
  4. Ground water cooling
  5. Surface water cooling
  6. Evaporative cooling, direct or indirect
  7. Desiccant dehumidification and evaporative cooling, using waste heat
  8. Absorption cooling, using waste heat
  9. The building does not require any significant form of active cooling or mechanical ventilation (i.e. naturally ventilated).

CN3.2 

Free cooling scope The free cooling should apply to all occupied spaces in the building. Small IT rooms and lift motor rooms are excluded. Mechanical ventilation may only be used for small areas, e.g. for kitchenettes and toilets.

CN3.3

LZC feasibility study

See criterion 7.

The LZC study should cover as a minimum:

  1. Energy generated from LZC energy source per year
  2. Carbon dioxide savings from LZC energy source per year
  3. Life cycle cost of the potential specification, accounting for payback
  4. Local planning criteria, including land use and noise
  5. Feasibility of exporting heat/electricity from the system
  6. Any available grants
  7. All technologies appropriate to the site and energy demand of the development.
  8. Reasons for excluding other technologies
  9. Where appropriate to the building type, connecting the proposed building to an existing local community CHP system or source of waste heat or power OR specifying a building/site CHP system or source of waste heat or power with the potential to export excess heat or power via a local community energy scheme.

CN3.4 

LZC feasibility study timing

See criterion 7.

When undertaking a feasibility study at a stage later than Concept Design (RIBA Stage 2 or equivalent), an additional element would need to be included in the report to highlight the local LZC energy sources which had been discounted due to the constraints placed on the project by the late consideration, and the reason for their omission. If the feasibility study discounted all local LZC as infeasible due to the late stage in the project that the study was commissioned, then the credit for the feasibility study must be withheld.

If the feasibility study were commissioned at the Concept Design stage or earlier, and in the unlikely event the study concluded that the specification of any local LZC technology were infeasible, the LZC credit could still be awarded.

CN3.5

Recognised local LZC technologies

See criterion 7.

Technologies eligible to contribute to achieving the requirements of this issue must produce energy from renewable sources and meet all other ancillary requirements as defined by Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC www.eur-lex.europa.eu/en).

The following requirements must also be met:

  1. There must be a direct supply of energy produced to the building under assessment.
  2. Where covered by the Microgeneration Certification Scheme (MCS), technologies under 50kWe or 45kWth must be MCS (or equivalent) certified products installed by MCS (or equivalent) certified installers.
  3. Combined heat and power (CHP) schemes above 50kWe must be certified under the CHPQA standard.

CHP schemes fuelled by mains gas are eligible to contribute to performance against this issue.

  1. Air source heat pumps can only be considered as a renewable technology when used in heating mode. Refer to Annex VI of Directive 2009/28/EC for more detail on accounting for energy from heat pumps.
  2. Where MCS or CHPQA certification is not available, the design team must investigate the availability of alternative accreditation schemes in line with the Directives listed above, or an equivalent country/regional directive or standard. Where an accreditation scheme exists it should be used for the purpose of verifying compliance of the specified LZC technology. If no accreditation scheme exists in the country, the design team must demonstrate they have investigated the competence of the installer selected to install the LZC technology and are confident that they have the skill and competence to install the technology appropriately.

CN3.6

Novel LZC technology not listed

See criterion 7.

Other systems may be acceptable as part of a LZC strategy under this issue but are not currently included as LZC technologies in any of the approved building energy calculation software packages. Acceptability will be dependent on the nature of the system proposed and the carbon benefits achieved. The BREEAM assessor must confirm acceptability with BRE before an assessment is submitted. The calculation procedure for the new LZC technology should be submitted for consideration as a 'novel technology' to be included in the 'SBEM-Q' innovation process

(see Other information ).

The novel technology would only be acceptable for the LZC credit if EITHER:

  1. It is already demonstrably modelled in one of the approved dynamic simulation compliance tools;
  2. The calculation procedure has been accepted by the SBEM-Q process and integrated into the SBEM tool; OR
  3. It has been applied for and is in the process of being accepted for SBEM-Q.

For one-off LZC technology designs, where it is not viable to obtain SBEM-Q approval, a BREEAM innovation credit can be applied for and subject to approval, obtained instead.

CN3.7 

Waste heat from a building- related operational process

See criterion 7.

Waste heat from an operational process that takes place within the assessed building (or on the assessed site) can be considered as ‘low carbon’ for the purpose of this BREEAM issue. This is on the condition that the generation of the heat from the process is integral to the assessed building. Examples of operational processes and functions include manufacturing processes, high temperature oven/kiln, compressors serving process plant, micro-brewery, crematorium, testing and commissioning boilers for training or manufacture, and data centres. It does not include waste heat from IT or server rooms, which could be used as part of conventional heat recovery measures.

CN3.8 

Community and near-site schemes

See criterion 7.

‘Local’ does not have to mean on-site; community schemes (near-site) can be used as a means of demonstrating compliance, as this BREEAM issue seeks to encourage the installation of on-site and near-site LZC technologies.

CN3.9 

Waste incineration

See criterion 7.

Waste heat from an incineration plant can only be considered as low carbon for the purpose of this BREEAM issue under the following circumstances:

  1. All other LZC technologies have been considered and discounted in the feasibility study and; EITHER
  2. The local authority or region in which the incineration plant is located is demonstrably meeting its annual waste reuse/recycling targets and waste management policies; OR
  3. There is a near or on-site facility connected to the building, via a private wire arrangement, which is demonstrably removing reusable and recyclable waste material prior to incineration.

CN3.10 

First generation biofuels

See criterion 7.

Given the current uncertainty over their impact on biodiversity, global food production and greenhouse gas savings, plus the ease of inter-changeability between fossil fuels, BREEAM does not recognise or reward building systems fuelled by first generation biofuels manufactured from feedstocks, e.g. biofuels manufactured from sugars, seeds, grain, animal fats etc. where these are grown or farmed for the purposes of biofuel production. Subject to review against the criteria set out in compliance note CN3.11, BREEAM may recognise systems using second generation biofuels (see Relevant definitions) or biofuels manufactured from biodegradable waste materials e.g. biogas, waste vegetable oil or locally and sustainably sourced solid biofuels e.g. woodchip, wood pellets, where these are not interchangeable with fossil fuels or first generation biofuels.

CN3.11

Second generation biofuels and biofuels from waste streams

See criterion 7.

BREEAM recognises that biofuels produced from biomass which is a by product of other processes may provide a more sustainable alternative to fossil fuels. Typically, these use waste feedstock consisting of residual non-food parts of current food crops, industry waste such as woodchips, other waste vegetable matter and waste fish oil from sustainable fish stocks to produce biofuel. Such biofuels will, in principle be recognised by BREEAM for the purposes of defining low/zero carbon technologies. However due to the emerging nature of such technologies, full details would be required for review by BRE Global prior to confirmation of acceptability. Matters which would be required for consideration include the following:

  1. Type, provenance and sustainability of the biomass feedstock
  2. Avoidance/minimisation of fossil fuel use in extracting the biofuel
  3. Minimising fossil fuel use in transporting the biomass/biofuel
  4. Presence of a supply agreement and a robust supply chain
  5. Compatibility of the biofuel with the specified boiler/plant and manufacturer’s warranty issues

The use of other recycled or waste-derived biofuels such as waste oil from catering may also be recognised by BREEAM subject to the above criteria. For smaller scale applications, the assessor will, in addition, be required to demonstrate that the biofuel is locally sourced. BREEAM does not qualify the term ‘locally sourced’ or specify a minimum supply contract. However the assessor must determine and demonstrate that these are reasonable for the particular application.

CN3.12

Meaningful reduction

See criteria 3 and 8.

The amount of energy or CO2 emissions reduction is not specified in the criteria in this issue. However, it should not be a trivial amount. As a guide, the installation should contribute at least 5% of overall building energy demand and/or CO2 emissions.
Building type specific

CN4 

Schools: information communication technology (ICT) classrooms With respect to the free cooling credit, it is possible for ICT classrooms to be designed to avoid the use of active cooling. Hence, they are not exempt from the requirements of this issue, i.e. if active cooling were used to treat these spaces, it would not be possible to achieve the free cooling credit within this BREEAM issue.

Methodology

Passive design analysis

Any savings resulting from the incorporation of passive design measures should be demonstrated by comparing the energy demand and / or CO2 emissions for the building with and without the proposed passive design measures adopted, as identified in the passive design analysis.

To enable a baseline for comparison to be established, a ‘standard building’ should be modelled with fabric performance equivalent to that of the local Building Regulations Notional Building (or for Scotland, an equivalent compliant building) and without the passive design measures (where feasible i.e. building orientation is likely to be fixed). The glazing areas should remain the same in both models.

With the exception of any changes to account for passive design measures and fabric performance, this ‘standard building’ should be modelled as equivalent to the actual building.

Any savings in energy demand and / or CO2 emissions should then be calculated by comparing the respective Building Emission Rate (BER) outputs from two building models representing the ‘proposed building’ specification (fixed at a point as agreed by the project team and assessor), and the ‘standard building’ specification.

These calculations should be carried out by a building services engineer who is a Member of The Chartered Institute of Building Services Engineers (CIBSE) or by an accredited energy assessor (see Ene 01 Reduction of energy use and carbon emissions – Relevant Definitions).

Free cooling analysis

The free cooling demand reduction is demonstrated by estimating the cooling and mechanical ventilation energy savings with free cooling measures compared with the total building services energy demand with the other passive design measures from the passive design analysis. The calculation methods should be the same as for the passive design analysis, as far as possible. Where the free cooling approach(es) chosen cannot be adequately modelled by these methods, the use of an/any alternative method(s) should be justified by the building services engineer or accredited energy assessor, demonstrating that it is/they are appropriate.

Low and zero carbon feasibility study

The demand reduction with the low and/or zero carbon (LZC) technologies is demonstrated by comparing regulated carbon dioxide (CO2) emissions with LZC technologies to the actual building regulated emissions without LZCs. When the CO2 savings are compared for different technologies, they may be estimated separately from the building energy model where appropriate, e.g. by using manufacturers' data, simple hand calculations and/or spreadsheets. For the specified technology/technologies, the demand reductions are modelled using dynamic simulation modelling. The energy supply used for the base case is mains gas and grid electricity. If mains gas were not available at the site, then oil may be used instead. The base case includes any passive design or free cooling measures adopted for the first two credits. The actual building energy demands are calculated as for the passive design analysis. The carbon dioxide emissions factors used for the Building Regulations calculations are then applied.

Evidence

Criteria Interim design stage Final post construction stage
All One or more of the appropriate evidence types listed in The BREEAM evidential requirements section can be used to demonstrate compliance with these criteria.
4

Results from a dynamic simulation model demonstrating the feasibility of the free cooling strategy.

As per interim design stage.

7 Results from a dynamic simulation model demonstrating demand reductions from the specified low zero carbon technology. As per interim design stage

Additional information

Relevant definitions

Approved building energy modelling software
Refer to Ene 01 Reduction of energy use and carbon emissions.
Energy specialist
An individual who has acquired substantial expertise or a recognised qualification for undertaking assessments, designs and installations of low or zero carbon solutions in the commercial buildings sector and is not professionally connected to a single low or zero carbon technology or manufacturer.
First and second generation biofuels
First generation biofuels are fuels made from sugar, starch, vegetable oil, or animal fats using conventional technology. Second generation biofuels are fuels from lignocellulosic biomass feedstock using advanced technical processes1Sustainable Bioenergy: a framework for decision makers, United Nations – Energy, 2007.. Common first generation biofuels include vegetable oil, biodiesel and bioalcohols.
Free cooling
The ability of the building to provide cooling to the internal occupied areas without the need to rely on energy consuming mechanical cooling. Free cooling is an enhanced passive design method that requires engineering design and modelling to demonstrate its effectiveness. Other similar methods include enhanced passive ventilation and enhanced daylighting.
Microgeneration Certification Scheme (MCS)
The Microgeneration Certification Scheme (MCS) is an independent scheme that certifies microgeneration products and installers in accordance with consistent standards. It is designed to evaluate microgeneration products and installers against robust criteria, and provides consumers with an independent indication of the reliability of products, assurance that the installation will be carried out to the appropriate standard and a route for complaints should there be any issues. The MCS is a United Kingdom Accreditation Service (UKAS) accredited certification scheme covering all microgeneration products and services. It has support from the Department of Energy and Climate Change (DECC), industry and non-governmental groups as a prime method for making a substantial contribution to cutting the UK’s dependency on fossil fuels and carbon dioxide emissions.
Near-site LZC
Refer to Ene 01 Reduction of energy use and carbon emissions.
On-site LZC
Refer to Ene 01 Reduction of energy use and carbon emissions.
Payback period
The period of time needed for a financial return on an investment to equal the sum of the original investment.

Other information

Free cooling aim
Free cooling has been highlighted in this issue as it relates particularly to contributing to reducing overheating for adaptation to climate change. It can also make the building much simpler to operate and maintain than one with mechanical cooling.
Novel low and zero carbon (LZC) technologies - SBEM-Q
In order to deal with the integration of new technologies into SBEM, a new procedure has been established which mirrors the SAP Appendix Q approach to some extent. Appendix Q provides a means whereby validated individual branded product performance information can be accessed and used as an adjunct to the SAP calculation. A product’s performance information is determined by testing against a specification that has been agreed by DECC’s NCM contractor, the relevant manufacturer(s) and industry sector representatives. Product data are listed in the SAP Appendix Q database (at:www.ncm-pcdb.org.uk/sap). By following the ‘Innovation' path from that website, manufacturers can apply for novel LZC technologies to be validated under the so-called ‘SBEM-Q’ procedure and then integrated as part of an amendment to the SBEM calculation.
LZC feasibility study in Building Regulations
The European Union Energy Performance of Buildings Directive (EPBD) (recast) 2012 (Directive 2010/31/EU), requires that all member states have a methodology for calculating the energy performance of buildings and that the feasibility of high efficiency alternative systems is considered before construction starts, including energy from renewable sources, cogeneration, district heating and cooling and heat pumps (Article 6). This requirement has been included in the building regulations for England (amendment Regulation 25A, 2013) and Scotland (October 2013) and it has been proposed for the forthcoming regulations in Wales, expected in July 2014. The LZC feasibility study in BREEAM is intended to encourage the study to be done early in the project, not just before construction starts, so that the most appropriate solutions can be adopted. Also, this credit does not permit technologies that are not best practice/sustainable or cannot be modelled with a robust method.
Passive design aim
Unlike the Ene 01 - Reduction of energy use and carbon emissions (which is focused on demonstrable and robust performance improvement), Ene 04 - Low carbon design aims to encourage project teams to consider a particular design approach.
In relation to the passive design credit, this is mostly reflected in criterion 2; the passive design analysis which is intended to encourage project teams to proactively consider the ways in which the building could benefit from, and adopt passive design measures (such as those listed in CN3).


BREEAM UK New Construction non-domestic buildings technical manual 2014
Reference: SD5076 – Issue: 5.0
Date: 23/08/2016
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