What are the new Building Regulations?

11th Apr, 2022

New building regulations come into force from 15 June 2022, covering ventilation, overheating and the conservation of fuel and power. There is a little bit of breathing space for developments already in the planning stage, with a one-year transition period to allow planning applications to run their course.

In all, the Government is introducing five Building Regulation Approved Documents (A.D.) as it works towards meeting the Future Homes and Buildings Standard, due in 2025.

The five documents are:

  • Approved Document F vol. 1: Ventilation (Domestic)
  • Approved Document F vol. 2: Ventilation (Non-Domestic)
  • Approved Document L vol. 1: Conservation of Fuel & Power (Domestic)
  • Approved Document L vol. 2: Conservation of Fuel & Power (Non-Domestic)
  • Approved Document O: Overheating

In this article, Services Design Solution will take you through the key changes and make suggestions to assist compliance. Please check out our flashcards for specific requirements.

We will discuss Approved Document L first, as the changes to the regulations covering fuel and power have a subsequent knock-on effect on those for ventilation.

Approved Document L vol. 1: Conservation of Fuel & Power (Domestic)

Under the new regulations, CO2 emissions in new build homes must be 30% lower than the existing standards, which have been in place since 2013. Part L amendments also introduce primary energy as a performance metric to evaluate energy efficiency. This metric replaces CO2 emissions within the building as the principal performance measure. From 15 June 2022, the primary energy metric will consider how power reaches the building. The definition of ‘primary energy’ in Standard Assessment Procedures is typically ‘energy from renewable and non-renewable sources which has not undergone any conversion or transformation process’.

In addition, Document L vol. 1 proposes increased building fabric performance levels for new construction elements, achieving a thermal transmittance (U-values), no greater than:

External walls: 0.18 W/m²K
Floor:                   0.13 W/m²K
Roof:                     0.11 W/m²K
Windows:           1.2 W/m²K

Services Design Solution Recommendation: To aid compliance with fabric energy efficiency and energy use reduction, we suggest a minimum of 0.15 W/m²K for walls, 0.12 W/m²K for floors, 0.10 W/m²K for roofs and 1.2 W/m²K for windows.

In new or replacement wet heating systems, the maximum flow temperature of the heating medium needs to be 55°C. This means there is a requirement for periodic water pasteurisation to 60°C to eliminate legionella risk. We anticipate air source heat pumps being the de-facto heat source post-2025.

Heat pump systems need to achieve a minimum Seasonal Coefficient of Performance (SCoP) for heating of 3.0 and cooling of 4.0. Domestic hot water systems require a minimum SCoP of 2.0.

Showers are now required to have waste-water heat recovery. The specification of the waste-water heat recovery units should make sure there is no legionella transfer.

Mechanical ventilation heat recovery systems (MVHR) should have a minimum heat recovery of 73%.

Services Design Solution Recommendation: We recommend a minimum heat recovery of 80%.

Luminaires should have a minimum efficiency of 75 lamp lumens per circuit watt for internal and external lighting. 105 lamp lumens per circuit watt can be easily achieved through LED lighting solutions.

The introduction of photovoltaic (P.V.) arrays has tremendously impacted reducing carbon emissions. The new amendments allocate the benefit of P.V. systems as allocatable to the ground floor area.

Download Approved Document L vol.1 on the government website

Approved Document L vol. 2: Conservation of Fuel & Power (Non-Domestic)

New non-domestic buildings need to achieve a 27% reduction in carbon emissions compared to the current standards set in 2013.

Methods of achieving the 27% reduction, as outlined in the document, include:

Increased thermal efficiency, using low U-values – using building materials that keep the cold out and the heat in, high-quality wall and roof insulation, and efficient windows and doors.

Providing energy-efficient lighting – lighting installations in new non-domestic buildings must achieve a minimum of 95 luminaire lumens per circuit watt for general lighting and 80 for display lighting. These can be aggregated so that low efficiency in some parts can be offset by high efficiency elsewhere. A separate lighting standard requiring a high level of optical performance has also been introduced.

Control systems – A building automation and control system is now mandatory for new non-domestic buildings with a heating or air-conditioning system over 180kW. Likewise, controls systems must be provided to heating and domestic hot water installations in existing non-domestic buildings to increase their efficiency.

A further change means that the air permeability testing of non-domestic buildings must adopt CIBSE’s ‘TM23 Testing buildings for air leakage’ methodology.

Buildings in England other than dwellings also require an ‘energy forecast’ as a part of the building logbook for new buildings over 1,000m² (total useful floor area), with CIBSE’s ‘TM54 Evaluating operational energy use at the design stage’ referenced as an ‘energy forecasting’ methodology (H.M. Government, 2021).

Download Approved Document L vol.2 on the government website

Approved Document F vol. 1: Ventilation (Domestic)

Approved Document Part F (Ventilation) is linked to A.D. Part L (Conservation of Fuel & Power). Measures to improve energy efficiency include reducing heat loss through air permeability. Therefore, new homes must be more efficient in keeping cold air out. The problem with dwelling air-tightness is the effect on reducing ventilation. As a result, Document F on homes was updated to provide ventilation to provide adequate fresh air.

The new ventilation requirements cite the importance of selecting an appropriate ventilation system and correct system installation to deliver an adequate air change rate and achieve reasonable air quality.

The regulations require dwellings with an air permeability of 3.0 or less to have continuous background mechanical ventilation. The target airflow rates remain the same, and the rules of ventilation rates to different dwelling types have been simplified.

Passive stack, system 2, and positive impact ventilation (PIV) are no longer part of the new regulations.

In the instance that natural ventilation is feasible without mechanical extract, background ventilators must have a larger cross-sectional area. Where intermittent and continuous extract systems are installed, sufficient background ventilators must be provided. The background ventilators are likely to cause an increase in internal noise levels due to external noise break-in. We recommend consulting an acoustic engineer during the design process.

When checking the installation and commissioning of the ventilation in new dwellings, consideration should be given to the following:

  • Make sure that no more than one type of intermittent, continuous, and mechanical ventilation with heat recovery (MVHR) system is included within a single dwelling
  • Intermittent extracts (such as cooker hoods or w.c. extracts linked to PIR switches require only a single flow reading for compliance
  • Continuous extracts, such as MVHR units, require two readings and must be compliant with the pre-calculated, latest-designed figures. These should be submitted in advance to the Building Control Officer
  • MVHR systems require a set of building calculations in addition to the testing and commissioning certificates of the installed system
  • Flexible duct is limited to a maximum length of 1.5m to reduce specific fan powers and associated auxiliary energy demand

We have provided Part F air flow targets for new dwellings in the flashcards.

Download Approved Document F vol.1 on the government website


Approved Document F vol. 2: Ventilation (Non-Domestic)

The ventilation requirements for commercial buildings remains much the same as before. However, some new guidance has been introduced, focusing on the need to minimise external pollutants and install effective ventilation systems.

Designers are afforded a degree of flexibility. The performance-based ventilation standards allow them to assess their ventilation strategies against individual volatile organic compounds (VOC), based on data from Public Health England, as an alternative route to using a total VOC limit.

It is recommended that replacement windows in non-domestic buildings are fitted with background trickle ventilators. But this will not be necessary in cases where a mechanical ventilation system is present, or where it can be shown that replacement windows would not adversely affect ventilation.

If external noise is a potential problem, attenuating background ventilators should be installed.

The standards require increased ventilation rates in shared spaces such as offices. There is an additional, new requirement to install CO2 monitors in rooms where airborne infection is considered a higher risk.

Ventilation intakes should still be located remotely from local pollution sources, following CIBSE’ TM40 health and wellbeing in building services’ and ‘TM64 Operational performance: Indoor air quality’.

Ventilation flow rates for offices are similar to 2013 levels:

  • Toilet extract: at 6 l/s per appliance
  • Urinals, showers or baths 15 l/s
  • Kitchenette areas with a microwave 15 l/s
  • Kitchens with cooker 30-60 l/s

Office ventilation supply rates remain at 10 l/s/person as a base. However, there is a new obligation to provide a ventilation rate of at least 1 l/s/m² of floor area, whichever is greater.

Common areas such as corridors and lobbies also require natural ventilation openings equal to one-fiftieth of the floor area. For mechanically ventilated solutions, a ventilation rate of at least 0.5 l/s/m² of the floor area must be provided.

Download Approved Document F vol.2 on the government website

Approved Document O: Overheating

While Approved Document F and L are updates to existing Building Regulations, AD O is a new publication recognising the need for measures to reduce the potential of overheating in dwellings. It sets standards in all new residential buildings, including dwellings, care homes, student accommodation and children’s homes.

England is divided into areas of moderate and high risk of overheating. High-risk locations are parts of central London and some areas of Central Manchester. Moderate risk locations are the remaining areas in England not labelled high risk. The postcodes of the high-risk areas are listed in Appendix C of the approved document.

Part O requires overheating mitigation strategies that are safe and usable by occupants. Potential issues such as external noise, air pollution, and window security must be considered when developing strategies. Information on overheating strategies must be given to the building owner in the form of a Home User Guide.

There are two methodologies for demonstrating compliance with Approved Document O:

  1. Dynamic thermal modelling. Applying CIBSE ‘TM59 Design methodology for the assessment of overheating risk in homes’. Acceptable strategies for limiting excess solar gain must be permanent fixtures and not removable mitigations such as fitted blinds or tree cover.
  2. The Simplified Method. Reducing risk by minimising solar gain and removing excess heat. It sets standards based on whether the residential unit is cross-ventilated, considers orientation and introduces a standard for the maximum amount of glazing allowed in a single room.

New houses across England must be provided with openings on opposite façades, allowing for crossflow ventilation. There can be two or fewer fabric elements and openings on facades that are not opposite for new flats and residential units.

Using the simplified method of compliance, there is a maximum limit of glazing on new domestic properties. This maximum area is 13% for high-risk dwellings on houses and 15% on apartments. This figure can be increased to up to 21% in domestic properties within moderate-risk locations.

Download Approved Document O on the government website