Have your say on overheating and the Fabric Energy Efficiency Standard in new homes

Please note - this article is for information only and LABC Warranty does not perform a regulatory role. Should you have any questions or concerns relating to Building Regulations please speak to your local LABC Building Control Team.

A second major consultation to inform the Future Homes Standard proposes an uplift in Fabric Energy Efficiency Standards (FEES) and new measures to reduce the risk of overheating in new homes in England.

While the second part of the Future Buildings Standard consultation is principally concerned with non-domestic dwellings, it includes a section covering a Government rethink over its original proposal to remove FEES from Approved Document L, Volume 1: Dwellings (Conservation of fuel and power).

The consultation also considers introducing a new legal requirement for all developers of homes in England to meet the same overheating standard.

Finally, the consultation explores uplifting standards in Part L and Part F (Ventilation) for renovation and refurbishment works in existing homes.

This articles focuses on the new-build domestic elements of the consultation.

FEES to be retained in Part L

In the original Future Homes Standard consultation from 2019, the Government proposed removing the FEES metric from Part L to reduce complexity. Following a strong response, options put forward now will mean that FEES are retained in Part L.

The Government’s proposed approach is to set a full fabric specification as per the table below, ensuring a “meaningful uplift to the fabric of new homes.” Other options consider higher or lower specification variations of this.

Fabric specifications for the Part L 2021 notional building

Fabric Element

Specification

Windows

1.2 W/m2.K

Doors

1.0 W/m2.K

External Walls

0.18 W/m2.K

Roof

0.11 W/m2.K

Floor

0.13 W/m2.K

Air Permeability

5m3/(h.m2) @50Pa

Party Wall

0 W/m2.K

New standards to reduce the risk of overheating in new homes

According to research carried out in 2019, most new homes across many locations in London and England can suffer from overheating.

The consultation proposes that a new legal requirement would form a new part of Schedule 1 of the Building Regulations, mandating measures to reduce overheating risk by limiting solar gains and removing excess heat.

Proposed buildings in scope would include residential dwellings including flats, care homes or similar buildings where people sleep on the premises, residential colleges, halls of residence and living accommodation for children aged five years and older.

Similar to the plot-by-plot transitional arrangements for the new Part L requirements, the proposal asks whether this transitional method should be adopted for overheating, rather than the usual development-wide approach.

A draft Overheating Approved Document provides guidance on meeting the requirement, outlining two compliance methods, a so-called “simplified method” and a “dynamic thermal analysis method.”

The simplified method of tackling overheating

The “simplified method” uses a combination of limiting unwanted solar gains and removing excess heat in order to reduce overheating risk.

The requirement depends on the location of the new residential building, with a geographical split proposing differing requirements for buildings in England and Greater London.

Requirements would also split down house-type lines:

  • Group A homes featuring more than two fabric elements and openings on opposite facades, allowing for cross ventilation.
  • Group B homes, mostly flats and residential units in larger buildings that have two or fewer fabric elements, and openings on facades which are not opposite

The dynamic thermal analysis method

This uses CIBSE’s TM59 Design methodology for the assessment of overheating risk in homes to demonstrate compliance with the new regulation for overheating. Location, materials’ properties, orientation, air change rates and an occupancy scenario is used to calculate the risk of overheating.

Again, two means of achieving compliance with the dynamic thermal analysis method are being proposed.

One is to limit solar gains using any combination of the following:

  • Fixed shading devices, such as shutters, external blinds, overhands and awnings
  • Glazing design, using size, orientation, g-value and size of window reveal
  • Building design, such as placement of balconies
  • Shade of adjacent buildings, structures or landscape

The second is to remove excess heat from the indoor environment, using:

  • Open windows
  • Ventilation louvres in external walls
  • Mechanical ventilation system

Whichever method is used, the consultation also seeks views on avoiding “unacceptable noise” into bedrooms, and it proposes a new requirement to provide the building owner with information on the overheating strategy.

Building automation and control systems in new homes

While the consultation’s focus falls more on replacement systems for existing homes, there are a few questions relating to Building Automation and Control Systems (BACS) that would apply to new-build dwellings.

They relate to system specification, commissioning and providing information to the homeowner, and are covered in sections 6, 8 and 9 of the draft Approved Document L, Volume 1: Dwellings.

Consultation timeline and next steps

With proposed changes for two Approved Documents covering domestic and non-domestic buildings being considered at the same time, the timeline can be confusing. The diagram below, provided by Government, gives a basic outline of the consultation roadmap.

Part L consultation roadmap

Contents of the Future Homes Standard and Future Buildings Standard consultations.

i - The Fabric Energy Efficiency Standard (FEES) is being re-consulted on in this consultation

The Future Buildings Standard consultation runs until 13 April 2021. Further information and documents can be found on the Government’s website.

 

Please Note: Every care was taken to ensure the information in this article was correct at the time of publication. Any written guidance provided does not replace the reader’s professional judgement and any construction project should comply with the relevant building regulations or applicable technical standards. However, for the most up to date LABC Warranty technical guidance please refer to your risk management surveyor and the latest version of the LABC Warranty Technical Manual.

Was this post helpful? /