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Future Buildings Standard: Building Regulations Part L and F, and overheating

Objectives of the consultation

This consultation was the second stage of 2-part consultation on proposed changes to Part L (Conservation of fuel and power) and Part F (ventilation) of the Building Regulations. It built on the Future Homes Standard consultation by setting out energy and ventilation standards for non-domestic buildings, existing homes and included proposals to mitigate against overheating in residential buildings.

It also covered the future of non-domestic standards through the Future Buildings Standard, which will deliver highly efficient non-domestic buildings which use low-carbon heat, ensuring they are better for the environment and fit for the future.

This consultation package sought views on the following areas:

Non-domestic buildings

  • A vision for the Future Buildings Standard that we propose will start to apply to new non-domestic buildings from 2025 onwards;
  • The Government’s preferred option to uplift energy efficiency standards for new non-domestic buildings in 2021 which is intended to deliver a 27% reduction in carbon emissions on average per building compared to the existing Part L standard. As well as improving the energy efficiency of new buildings in the short term, the interim uplift will ensure that construction professionals and supply chains are working to higher specifications in readiness for the proposed introduction of the Future Buildings Standard from 2025;
  • Improvements to the non-domestic energy modelling methodologies;
  • Improvements to standards when work is carried out in existing non-domestic buildings;
  • Changes to Part F (ventilation) and its associated Approved Document guidance, for both new and existing non-domestic buildings; and
  • Proposals to introduce a new overheating mitigation requirement in the Building Regulations for new non-domestic buildings which are classed as ‘residential’.

Domestic buildings

  • Proposals to introduce a new overheating mitigation requirement in the Building Regulations for new homes;
  • Improvements to standards when work is carried out in existing homes;
  • Reconsulting on the Fabric Energy Efficiency Standard, as well as other standards for building services in new homes and guidance on the calibration of devices that carry out airtightness testing; and
  • Changes to Part F (ventilation) and its associated Approved Document guidance.

The consultation closed on 13 April 2021.

Supporting papers

To download documents, which supported this consultation, follow the links below.

CIBSE response

In addition to our full response, CIBSE together with a number of prominent organisations signed a letter to the Secretary of State to express our key messages.

CIBSE welcome a number of aspects in the Future Homes Standard (FHS) response and the Future Buildings Standard (FBS) consultation, which we had called for in our response to the 2019-20 FHS consultation and other policy positions:

  • The overall stated intention that from 2025, buildings should not need to be retrofitted to be net zero carbon in 2050. This is an essential first step towards delivering new housing that can achieve net zero standards without significant further cost to the homeowner or landlord and without significant use of additional financial, time and embodied carbon resources.
  • Retaining the right for Local Authorities to set energy and carbon standards beyond regulatory minima, allowing more carbon savings earlier and ultimately developing the rest of the market
  • Accelerated development of the FHS, with a draft now due in 2023. This will allow early adoption by market leaders and local authorities and support the development of supply chains. 
  • Retaining fabric energy efficiency standards (FEES) whose removal created serious risks of fuel poverty and poor fabric performance. 
  • For non-domestic buildings, clear statements acknowledging the performance gap, with a strengthening of commissioning requirements, some changes to the NCM to “better account for energy uses and incentivise appropriate design solutions”, and the new requirement for energy performance modelling (e.g. CIBSE TM54) for buildings over 1,000 m2.
  • For non-domestic buildings, clear statements about the importance of heat decarbonisation, anticipating a central role for heat pumps and no role for hydrogen in the timescale considered.

However, there are a number of proposed measures which cause concern and may cause unintended consequences, and some measures which CIBSE considers necessary that are omitted. These concerns and omissions are set out below along with our recommendations for inclusion in the 2021 and 2025 revisions:  

Key points to address CIBSE recommendations for 2021 revision CIBSE recommendations for 2025 revision (i.e. Future Buildings / Homes Standard, but also including existing buildings / homes)
1 - Target setting and like-for-like-comparisons, to drive real reductions in energy use and heat decarbonisation For non-domestic buildings the 2021 uplift currently proposes to vary the heating fuel in the notional building e.g. district heating or gas if this is in the actual building. This provides artificial support factors for particular systems e.g. district heating networks would be allowed several times the emissions from heating than heat pumps, and significantly more than even from gas boilers: this is not enough incentive to heat decarbonisation now and to build supply chains.
Buildings and heat options must be evaluated on a like-for-like basis:
- All on-site options must be compared against the same baseline. This would provide a clear assessment of low-carbon heat options, and send a strong signal that the move away from gas is serious.
- While we accept there may be a transition period for district heating networks, 1) new networks must be evaluated on a like-for-like basis with on-site solutions; 2) existing networks must be assessed on a more ambitious basis than currently, which is with average plant and 100% fossil fuelled, and they must be required to produce a plan for decarbonisation.
The approach based on a notional building may have been appropriate when regulations sought relative improvements, but all opportunities need to be captured towards the net zero carbon target and there must be a clear way to assess and track progress. The notional building prevents like-for-like comparisons and does not drive optimisation of building form and orientation.
New buildings of the same type should be compared to the same target level of performance, an absolute target.  
In addition, the outline FBS should from now on set a clear end data for new fossil fuel installations, as the outline FHS does. This will give a clear direction and incentive for supply chains to develop.
2 – Metrics that support energy efficiency and heat decarbonisation The consultation proposes a dual metric system, introducing primary energy alongside carbon. Both these metrics mean little to consumers, especially primary energy. They rely on conversion factors which change over time, which does not facilitate tracking of progress over time, comparing buildings, nor creating a closer link with actual performance.
In addition, the consultation states that the benefit of using primary energy would be to drive reductions in electricity demand. However, our analysis shows that this is a flawed argument, as the primary energy factors for electricity completely follow its carbon factors: primary energy as a metric does not add any value.
Finally, and importantly, primary energy favours gas and other fossil fuels over electricity and therefore goes against heat decarbonisation.
We understand primary energy was introduced because the EPBD uses it, but Brexit provides an opportunity not to.
Instead of primary energy, energy use as metric alongside carbon emissions and fabric performance would better address the key goals of energy efficiency, carbon reduction, and consumer engagement.
Retain energy use as a metric alongside carbon emissions, and fabric performance. Review the need to introduce a metric or criteria to address demand management (e.g. peak demand and proportion that can be shifted).
3 - A commitment to actual performance, starting with disclosure Actual in-use performance beyond Practical Completion must be addressed, for example as part of the wider regulatory regime created in response to the Hackitt Review. As a very minimum, this should start with disclosure of actual energy use (broken down into fuels where applicable).
In addition to this, we recommend reviewing the possibility to introduce further in-use evaluation, monitoring and evaluation to match performance criteria in Building Regulations and the Approved Documents e.g. ventilation rates. We expect this should be possible within the existing framework of the Building Act (Section 2 – Continuing Requirements) and Building Regulations; however, we are aware that the clause on Continuing Requirements is difficult to interpret, and we also recommend that this lack of clarity needs addressing.
We have commented in detail on the proposed new overheating risk “simplified method”, including the request for more information on the rationale and testing carried out. Regardless of the final method implemented, as it is a new regulatory requirement and a new un-tested method, we strongly recommend that MHCLG should put together a programme of monitoring to test its implementation and gather lessons for the next revision. We would also recommend that Building Control reserve the right to request in-use monitoring of temperature and possibly feedback from occupants. However good the new method ends up being, there will be lessons to gather and incorporate, and this must be factored in right now.
The data collected from the 2021 disclosure requirement should inform the FHS and FBS and the setting of absolute rather than relative targets (see point 1).
The overheating methodology should be modified in line with lessons gathered from the first phase of implementation, including in-use monitoring and feedback.
In-use monitoring and evaluation requirements should be in place to match Building Regulations performance requirements.
4 – Commissioning New buildings will not be net zero carbon buildings unless they are commissioned. There needs to be greater focus on compliance with the commissioning requirements. It must become accepted that building control will expect to see and may make some checks on commissioning evidence then we will not achieve net zero. This may imply some training requirements for building control professionals, and it may require some procedures to support the greater focus, but without action it is not possible to claim that the changes to the regulations will achieve the intended carbon impacts.
Commissioning should very clearly include performance testing, and this could for example be linked to a penalty in as-built Part L calculations unless satisfactory results are provided to Building Control. This would benefit both energy efficiency and, for ventilation systems, air quality.
Continue as per 2021, and incorporate any lessons learnt.
Look to introduce digital returns of key information throughout the build process to simplify the cost of existing requirements and reduce the impact of additional information requirements. Such a system should be centralised and accessible to the Building Safety Regulator, allowing them to see easily where projects are not producing required information and therefore to target their compliance and enforcement efforts on topics where compliance is low, or on those parties not delivering, which in turn incentivises better compliance.
5 - Airtightness and ventilation For dwellings, the notional building specification of 5 m3/hr/m2 at 50Pa together with natural ventilation does not set the right direction to prepare supply chains for airtight buildings and highly efficient ventilation (even if other systems remain allowed).
For non-domestic buildings, a limiting value of 8 m3/hr/m2 at 50Pa is too high.
Testing requirements and limit airtightness values must be introduced on existing buildings and existing dwellings, at least where substantial works are carried out. This will improve performance and build quality, and support better informed decisions on both energy efficiency and ventilation. See also point 7 on whole-building approach
The draft FHS specification proposes an airtightness of 5 m3/hr/m2 at 50Pa, and natural ventilation. This is quite far from the "world class" levels of energy efficiency intended for the FHS and is a remaining important opportunity for energy savings. The FHS specification should show best practice airtightness and MVHR (even if other systems remain allowed). This would encourage the development of supply chains now so that MVHR is well designed and installed, and delivers energy savings and good indoor air quality.
6 – A trajectory for the existing stock For existing domestic and non-domestic buildings the consultation package only includes a 2021 revision, and it is a relatively modest one.
However, given the scale and performance of the existing building stock, it is clearly by far the biggest challenge to achieve net zero carbon buildings. Whilst this cannot be solved by Building Regulations alone, they are a key policy to drive some of the changes needed. It is therefore essential that work is done urgently to consider the role of Building Regulations in the decarbonisation of the existing building stock and to co-ordinate the various policies that influence the energy use of our building stock. The recent coronavirus response has highlighted the need to co-ordinate health requirements and energy requirements more closely, for example. It would be very helpful to see a clear and early indication that the challenge of existing buildings is a cross departmental policy issue and a cross disciplinary technical issue.
Government must commit to a 2025 upgrade and set out a programme of works to introduce upgraded requirements informed by evidence and supported by clear guidance on complex technical issues, such as dealing with traditional construction buildings, thermal bridging and moisture movement. This should incorporate lessons from recent exemplar retrofit projects, PAS 2035, past programmes such as Retrofit for the Future, and additional research if required. It should be on the same timescale as the development of the FHS/FBS.
Implement 2025 Future Homes & Buildings standard proposals for the existing stock
7 – A plan and a whole building approach for the existing stock Two serious limitations in the current requirements for existing buildings are that they do not provide an end goal compatible with net zero, and they rely heavily on an elemental approach. This doesn’t sufficiently make the links between energy, overheating, air quality, and fabric, and it doesn’t prevent carbon lock-ins and unintended consequences. All works covered by Building Regulations must contribute to the huge challenge of putting buildings on track to net zero, while being healthy and comfortable.
The Part F requirement that ventilation should be “no worse” than before the works is highly inadequate, as many homes are not well ventilated. The works should be “net zero ready”, and a longer-term plan should be produced for the building, to reduce operational, embodied, and financial expenditure now and in the future. It is the approach promoted in PAS 2035, which regulations should build on.
Continue as per 2021, and incorporate any lessons learnt. Start a programme gradually phasing out fossil fuel replacement plant in existing buildings/dwellings.
8 - Calculation methodologies that are fit to Net Zero There is little evidence that NCM drives improvements on non-domestic buildings. Space heating is known to be routinely under-estimated, clearly an issue for heat decarbonisation and the appraisal of options. Changes to NCM in 2021 should be more substantial changes than currently proposed, in particular on the calculation of energy use for heating.
MHCLG should also commit to a fundamental review of NCM to accompany the FBS, similar to that commissioned by BEIS for SAP/RdSAP 11.
Implement the conclusions of the fundamental review of SAP and NCM.

Competence, skills, and supply chains

Many of the topics and proposals detailed above will require significant skills updates and upgrades across the whole of the supply chain. They are not optional extras, they are essential to achieving the necessary successful outcomes from the measures detailed. Without a serious and sustained focus on skills over many years then significant aspects of the programme are in jeopardy from the outset. There are 2 particular areas where this is the case:

  • Airtightness and ventilation, to improve energy efficiency and protect the health of occupants
  • Low-carbon heat: Moving from a predominantly gas fuelled domestic sector to a predominantly electric fuelled one requires significant (re)training to deliver performance and protect consumers.

The outline Future Homes / Buildings Standard must clearly show what supply chains will be expected to deliver, so they can start preparing now, and the 2021 revision must represent a clear step towards 2025 requirements, to provide further incentives for supply chain development.

In addition, and recognising that this cannot be addressed by Building Regulations alone, MHCLG should work closely with BEIS to develop a buildings policy which covers safety, sustainability and skills. For a more detailed analysis please see the Royal Academy of Engineering paper "Beyond COVID-19: laying the foundations for a net zero recovery".

General comments on the consultation package

We acknowledge that a consultation seeking to tackle new and existing buildings, domestic and non-domestic, 2021 and 2025, and Parts L, F and overheating, was a significant challenge to produce, and we appreciate all the work which went into it. However, following our own analysis as well as the feedback we have received from several parties, we would like to raise concerns about some of the information provided which, together with the breadth of the consultation, may prevent MHCLG from gathering truly well-informed and thorough responses. The following items are of particular concern as they are significant topics for building performance, carbon emissions, and the health of occupants, and we are concerned about the quality of responses as a result. There may be others which we have not been able to spot: 

  • Question 17 – connection to existing district heating networks: erroneous carbon factor of the notional district heating network (0.19kgCO2/kWh stated in the draft NCM). We are grateful for MHCLG’s response to our query on this topic, and we have communicated this it to members who had raised it with us, to the LETI network, and via social media, but given the short timescale we are wary that a number of respondents will respond on the basis of “carbon factor of 0.19”.
  • Question 110 - FEES: Unclear wording (“high” or “low”), which was clarified to the LETI network and passed on to CIBSE, as we raised our concerns to them. This is a significant topic under consultation, and we are concerned about the ease of interpreting responses as a result.
  • New overheating standard and simplified method: as detailed in our response, we very much support the introduction of a regulatory standard on this issue, and support the principle of a simplified method. However, these are clearly significant changes, which could have long-term consequences on thousands of buildings and residents, and the proposals are currently difficult to assess thoroughly given the lack of explanatory material i.e. how the method was arrived at, and what testing was carried out on its robustness.
  • Changes and omissions e.g. Removal of reference to summer comfort appraisals for non-domestic buildings: the current draft ADL2 omits an important statement highlighting the limits of considering only summer gains, and recommending an assessment of thermal comfort in non-domestic buildings – see details in Question 53. Not only is this a change CIBSE strongly advise against, it is also a significant change which has not been highlighted in the consultation document and draft AD, nor covered by a consultation question. This is of specific concern for this topic, but also raises the question of whether other important changes are proposed, which have not been highlighted and are not covered by consultation questions. Faced with such a wide ranging and important consultation, industry cannot be expected to spot every single change or omission, and we are concerned that important ones may not have been raised and will consequently not receive the scrutiny and feedback they deserve.

To read the full CIBSE response, follow the link below.