Changes to Part L Building Regulations 2021

Photographic Evidence

Photographs should be taken for each dwelling as a record during the construction phase and made available to the Energy Assessor and Building Control body. Photographs should be taken at various stages for each detail listed below and should be unique to each property:

1.Foundation/substructure and ground, showing thermal continuity and quality of insulation.

a. At ground floor perimeter edge insulation.

b. At external door threshold.

c. Below damp-proof course on external walls.

2. External walls, for each main wall type showing thermal continuity and quality of insulation.

a. Ground floor to wall junction.

b. Structural penetrating elements.

3. Roof, for each main roof type showing thermal continuity and quality of insulation.

a. Joist/rafter level.

b. Eaves and gable edges.

4. Openings, for each opening type showing thermal continuity and quality of insulation.

a. Window positioning in relation to cavity closer or insulation line.

b. External doorset positioning in relation to cavity closer or insulation line.

5. Airtightness. Additional photographs of the above details showing airtightness measures if not included or visible in continuity of insulation images.

6. Building services, for all plant associated with space heating, hot water, ventilation and low or zero carbon technology equipment within or on the building.

a. Plant/equipment identification label(s), including make/model and serial number.

b. Primary pipework continuity of insulation.

c. Mechanical ventilation ductwork continuity of insulation.

All photographs should be digital and of sufficient quality and high enough resolution to allow a qualitative audit of the subject detail. Geo-location should be enabled to confirm location, time, and date of each image. Each image should be named such to include a plot number and detail reference according to the numbers used in the above paragraph. For example, Plot 1 eaves detail would be P1/3b.

Additional changes to new Part L 2021

New Compliance Requirements

Change to compliance criteria, now four items

• Primary energy –principal metric
• CO2–secondary metric
• Fabric Energy efficiency returns (DFEE & TFEE)
• Minimum Standard for fabric & fixed building services

Notional Building Fabric Specification

Notional Specification:

Full notional Specification is designed around a Gas Heating System (89.5%)

It includes the Fabric Spec plus the following additional plant –

Photovoltaic requirement is calculated based on the following:

• Houses: 40% of the Ground Floor Area ÷ 6.5
• Flat: 40% of the building GF area ÷ (6.5 x number of storeys)

All showers to be equipped with Waste Water Heat Recovery (WWHR)

Heating system design for max temperature of 55C

SAP10 consultation has updated national grid electricity Carbon Factors, so electricity Carbon intensity is almost the same as Natural Gas:

Reducing from 0.519kgCO2/kWh to 0.136kgCO2/kWh

Mains Gas is now at 0.210kgCO2/kWh

Appendix R Changes (Notional Building)

Key Changes:

• U-Value Changes
• Thermal Mass
• WWHRS
• PV
• Lighting

U-Value Changes –roofs, windows, rooflights (new), roof windows, semi/glazed doors, curtain wall glazing

Thermal Mass

Must be calculated in SAP 10

WWHRS new to appendix R

• The notional dwelling will recover 36% of previously wasted heat to be utilised as hot water
• Utilisation factor 0.98

Lighting

• 2012 –100% fixed outlets LEL (Low Energy Lighting)
• SAP10 -fixed lighting capacity (lm) = 185 x TFA (Total Floor Area)
• Efficacy of all fixed lighting = 80 lm/W
• This allows for efficiency above CFL’s (Compact Fluorescent Lighting) and penalises poorly performing luminaires

The calculation of lighting energy has been updated to allow for the lighting efficacy and amount

• Required evidence –power (P) and efficacy (E)
• Number of fixtures
• Capacity is automatically calculated with P & E
• Appendix L for Lighting easy to remember

Allowance for Battery Storage KWH

• Diverter present –only PV or hot water (not both)
• Battery Capacity –required information
• Surplus is assumed to be exported to the grid if the PV is connected to an export-capable meter. (10.2) -previously assumed

Showers and Baths

The calculation of hot water consumption has been adjusted to take account of the showers (number of), flow rate, number of baths

Appendix J (new)

Primary Energy

DPER –Dwelling Primary Energy Rating-The annual primary energy use of the building per unit floor area for space heating, water heating, ventilation and lighting, adjusted for any renewable primary energy generated on the site of the dwelling, expressed in kWh/m²/year.

• Table 12, -major changes to factors
• Electricity
• factor changes
• (2012) 3.07
• (SAP10) 1.501
• Anticipating phasing out of gas heating

Air permeability

All new dwellings must be tested, no more sample testing.

Accredited construction Details

Several changes are being made to the way thermal bridging is going to be calculated in SAP 10. These changes include;

ACDs are to be removed as they are deemed to be out of date and no longer work with fabric standards required to meet new regulations (accredited construction details have been archived)

There will be an increase in use of the details from other schemes; Constructive Details, CBA, BRE, LABC etc.

As an alternative more thermal junction modelling may be needed.

Overheating

It is anticipated that the SAP software will include the simplified method of determining the overheating risk to the assessment, but until approved documents are released the software will not include the new method.

A basic summary of overheating will follow:

• Appendix P has been removed from 10.2
• SAP is no longer required to include this function
• Approved Document (X) -details 2 methods of assessing overheating risk

1. Simplified method

2. Dynamic thermal analysis -Dynamic analysis to CIBSE TM59 can be completed.

The biggest changes

• Primary Energy as key metric
• Carbon factor for Electricity: 0.519 to 0.136
• Fuel cost difference between gas and electricity
• PV in appendix R (notional dwelling)
• WWHRS in appendix R
• Calculation of thermal mass
• Shower, baths and lighting inputs
• Thermal bridging ACD improvements
• PV battery or diverter
• Air testing all new dwellings
• Photographic evidence requirements