Glaring omissions: CIBSE response to building standards consultations

As the consultation period closes for a slew of regulations that will determine the sustainability of building stock for years to come, Julie Godefroy summarises CIBSE’s response to government proposals, and says they should have gone further to cut energy use and carbon

CIBSE has submitted responses to one of the largest consultation packages for energy and carbon regulations in buildings in recent years. It comprised the Future Homes Standard (FHS), Future Buildings Standard (FBS), Part O, and homes created through material change of use (MCU)1. A consultation was also published on the Home Energy Model (HEM) and its application to the FHS (HEM:FHS)2.

Apart from proposals for homes created through MCU, the package only addressed new buildings. There are currently no proposals for revising the regulations on works to existing buildings, which means that improvement opportunities continue to be missed when substantial works are carried out.

This adds to the government’s backtracking on minimum Energy Performance Certificate (EPC) ratings in rented properties in late 2023.

The consultation did not address embodied carbon. The Department for Levelling Up, Housing and Communities has been considering regulatory options on this for a couple of years. CIBSE continues to support the Part Z campaign2, an industry-proposed amendment to Building Regulations, and the government should come forward with proposals as soon as possible.

Both of these omit huge parts of the building stock’s carbon emissions, on which the Climate Change Committee has urged action.

HEM, the replacement for SAP

The consultation introduces HEM, and HEM:FHS, as a replacement for the Standard Assessment Procedure (SAP). HEM has added functionality and (hopefully) accuracy compared with SAP, but also added complexity and user inputs. A useful change is the distinction between the calculation methodology (= HEM), and the set assumptions and inputs to the calculation (= the FHS ‘wrapper’ – for example, the number of occupants and their activities). This paves the way for other useful applications – for example, wrappers for EPCs.

HEM could also be used outside of compliance calculations, with completely flexible inputs that would allow for the modelling of a home with its specific characteristics, such as number of occupants, heating patterns, and so on. 

In large part, the proposals lack ambition and are a missed opportunity to create buildings that will deliver low energy use

Positive moves

There are a few positive elements in the FHS/FBS package: a clear move away from fossil fuels for heating and hot water in new domestic and non-domestic buildings, and more attention to post-completion testing. The latter should be welcome, even if the proposals are somewhat vague. CIBSE recommends examining the feasibility of a rating scale, based on tested performance, that could be used across the stock and support householders’ decisions for rental, purchase and retrofit, rather than for new-build homes only.

Another positive move is more requirements on homes created by MCU, including energy and carbon, airtightness testing, and Part O. This is welcome to protect householders, as homes created through permitted development rights are often sub-standard.

In large part, however, the proposals lack ambition and are a missed opportunity to create buildings that will deliver low energy use and good indoor environments, and not need future retrofits.


CIBSE repeated a number of comments made in previous consultations and supported by others, including LETI, RIBA and the Good Homes Alliance.

There is a need to review the approach to metrics and targets, to drive improvements and better relate to measurable, in-use performance.

Fabric and ventilation requirements should be more ambitious to deliver low space-heating demand and better air quality. The proposals for fabric in new-build homes were the least ambitious of the Future Homes Hub options, and less ambitious than in the 2021 consultation, despite 84% of respondents at the time recommending more ambition. 

The requirements for an ‘energy forecast’ for non-domestic buildings of more than 1,000m2 can be met by methods that are not intended or suitable for it. This risks confusing designers and building owners, leading to work of little or no additional value being created. These forecasts should require energy performance modelling (for example, Passive House Planning Package, Nabers, or other methods in line with CIBSE TM54).

The FBS consultation acknowledged industry concerns about the National Calculation Methodology (NCM), including its tendency to underestimate space-heating demand (see the CIBSE-LETI response to the 2022 call for evidence3). However, the proposed changes seem very limited and insufficient.

A substantial review of the NCM should be carried out, so that the NCM better supports the implementation of energy efficiency measures in new and existing buildings.

Heat networks

The proposals came alongside the Heat Zoning consultation. CIBSE is concerned that the current proposals do not ensure that new-build networks offer a low carbon solution compared with onsite alternatives, or that they will drive the decarbonisation of existing networks. This is for a number of reasons, including the setting of the notional building when connected to a heat network, and the calculation methodology for carbon content of heat from networks.

Current consultations

Carbon border adjustment mechanism is a tax reflecting the carbon impact of imported products and materials. CIBSE is not currently planning to submit a response, but may contribute to the response of others. The consultation closes on 13 June. Please contact CIBSE by 31 May to feed into this.

The City of London 2040 City Plan and Sustainability Supplementary Planning Guidance includes a proposal for a ‘retrofit first’ approach. The consultation closes on 17 May, and contributions should be sent to CIBSE by 10 May. For more, see CIBSE News on page 10. 


  1. The Future Homes Standard (FHS), Future Buildings Standard (FBS), Part O, and homes created through material change of use (MCU), CIBSE consultation response,
  2. The Home Energy Model (HEM) CIBSE consultation response,, and Home Energy Model: Future Homes Standard Assessment CIBSE consultation response to its application to the FHS (HEM:FHS),
  3. NCM Call for Evidence – Joint Submission by CIBSE and LETI
  4. ‘Zoning in: the new Heat Network Zoning consultation’, CIBSE Journal, April 2023,
  5. Part Z,
  6. Consultation on the introduction of a UK carbon border adjustment mechanism,
  7. City of London 2040 City Plan and Sustainability Supplementary Planning Guidance,