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ENE 04 - Low carbon design

Information correct as of 5thMay 2021. Please see for the latest compliance information.

District heating systems – fuel mix - KBCN0885

Where the feasibility study is considering connection to a district heating system and this burns a mixture of fuels, only the proportion of output generated from second generation bio-fuels (or waste incineration that complies with BREEAM requirements) can be considered for this issue. For instance, a system burning a 25/75 mix of compliant biofuel vs fossil fuel can only count 25% of its output towards a meaningful reduction in CO2 emissions (where relevant to the BREEAM scheme) against the baseline building. As fuel mixes may vary over time, at least one year or more of historical information must be provided to balance out any seasonal variations. Where the system is new or proposed, robust evidence must be provided of the anticipated fuel mix. The fuel mix must be calculated based on the energy content of the input fuels in kWh.
19/12/2017 Wording clarified

Feasibility study – comparison with connection to existing LZCs - KBCN0563

In carrying out a feasibility study (covering all the areas required as stated in the manual) the primary intent is to demonstrate to a reasonable level of certainty that the chosen LZC is the most appropriate of all those available. Some of the options (for example community heating/cooling schemes) may not allow for a simple like for like comparison but a comparison can be made overall across many factors. For example in a community heating scheme the life cycle costing estimate might need to be simply the cost of using and maintaining the system for the measuring period, if upfront costs and payback period information is not available. Similarly for an existing community scheme, planning would not be a barrier but land use and noise impacts could be compared. The feasibility study must include a comparison of all criteria and for it to show that each has been factored into the final option being made. While some options may provide information in different formats and differing levels of detail making direct comparisons not straightforward, a comparison can still be made and this should aim to be as comprehensive and representative as possible. This will serve to demonstrate with reasonable certainty that the chosen option is the most appropriate. 

LCC – LZC energy sources discounted - KBCN0606

When sufficient information can be provided to justify that LZC energy sources are not appropriate for the development, the LCC analysis, for those LZC sources, do not need to be included in the feasibility study. The feasibility study (covering all the areas required as stated in the manual) intends to demonstrate, to a reasonable level of certainty, that the chosen LZC is the most appropriate of all those available.

LZC technologies – energy centre or other LZCs connected at a later stage - KBCN0267

If a project specifies LZCs that have been proposed in the feasibility report which reduce emissions, and/or will be connected to a site-wide energy centre operational at a later stage of the phased development, after the Post Construction Stage review has been submitted, the Energy and Pollution issues can be assessed as follows: In a phased development where the primary heating system will be upgraded at a later stage than the building being assessed, a commitment to install the new heating source must be made in the General Contract Specification (as per the BREEAM requirements). BREEAM does not specify a particular time for phasing as it is difficult to set parameters, however as a rule building users should have to wait the least time possible before they can use the upgraded heating source. For the quality audit, two Energy model outputs/EPCs must be produced at the final stage - one with the actual interim system installed for building control, and one for the BREEAM assessment which can include the predicted energy from the proposed energy centre.  Additionally, the legally binding general contract specification for the new heating source must be submitted with details of the timescales proposed for the completion of the second phase of work. Where this approach is to be followed BREEAM must be consulted in each case to ensure that the arrangements are sufficiently robust to award the credits. BREEAM seeks to recognise the environmental impacts of a building's energy use throughout its life, therefore temporary arrangements can be accommodated, provided there is robust evidence on future connection to the permanent systems.

LZC technologies – planning conditions and restrictions - KBCN0535

Where a mandatory planning condition exists (eg to attach to a District Heating Scheme), this will clearly affect the number of options available in a feasibility study. In such cases, compliance can still be achieved where evidence on the planning condition restrictions is provided, and it is clarified how this excludes other technologies from being considered. The feasibility study will still need to be carried out to cover the remaining energy needs of the building (eg Electrical and lighting load in the case of a district heating scheme).  

LZC technologies – shell only feasibility study - KBCN0409

For a shell only project, compliance may be assessed on the built form only i.e. demonstrating that sufficient space and clearance for the installation of future LZCs has been considered, the built form is suitably sited, and that massing and orientation are optimised for the future systems.

On-site LZC – whole site shared connection - KBCN1424

To be recognised in BREEAM, the on-site Low and Zero Carbon (LZC) technology must have a direct physical connection to the assessed building. OR Where the LZC technology is; it is acceptable to allocate the energy generated from this technology to the assessed building proportionally as a calculation of the building's predicted energy consumption compared to the total energy consumption of the whole site. To allocate renewable electricity by proportional consumption follow these steps; Where consumption data is missing, renewable electricity must not be allocated to the assessed building. In this case, it is assumed that all electricity consumed is sourced from the grid.

Passive design analysis – Modelling the standard building when existing building elements are retained - KBCN1270

In circumstances where an existing building element (e.g. a facade) is being retained it is acceptable to incorporate them into the modelling of the 'standard building' baseline, for the purpose of undertaking passive design analysis. All other building elements 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).

Passive design analysis where Hea 04 is not applicable - KBCN1236

Where Hea 04 is not applicable to the building type and options selected (for example an industrial building with no office areas), criterion 1 of Ene 04 is not applicable.

Thermal modelling for shell only developments - KBCN0784

For shell only developments, in order to achieve criterion 1, thermal modelling can be completed on the basis of a typical notional layout and equipment specification for the particular building type (retail, restaurants, cinema etc.) can be used to demonstrate compliance.
Information correct as of 5thMay 2021. Please see for the latest compliance information.