The government has initiated a consultation concerning the introduction of a new Building Regulation for overheating in new dwellings in England. These changes are expected to have a significant impact on glass and glazing products in residential buildings.
Approved Document
Ending on 13th April 2021, the consultation sets out proposals for a new Approved Document covering the mitigation of overheating risk in new dwellings in England. This follows on from an earlier consultation on new dwellings, the Government’s response to which has been published.
Solar Gains
Applying only to new dwellings, the Approved Document would require dwellings to be designed and constructed in such a way as to limit unwanted solar gains in summer. Also to provide an adequate means to remove excess heat from inside. Two methods of assessment are foreseen:
- Simplified method, related to location, dwelling type, glazing and floor area
- Detailed thermal analysis method, involving calculation of the risk of overheating
For the simplified method, England is split into two broad areas:
- England, excluding Greater London (with a moderate risk of overheating), and
- Greater London (with a significant risk of overheating)
Maximum Glazing Area
Using the simplified method, residential buildings should meet the maximum glazing area and shading standards in the table below.
Where shading is required, glazing with a maximum g value of 0.40 and a high light transmittance of 0.70 can be used.
Removing Heat Excess
In terms of removing excess heat, the proposals set a minimum free area (geometric open area of a ventilator). This is dependent upon floor and glazing areas and whether the building is in group A or B.
To satisfy the above requirements, Stella provides a range of glass products that can provide solar control and / or thermal insulation. This includes Pilkington Suncool™ 70/35. These include products that can meet the low g value glazing requirement of a maximum 0.40 as stated in the simplified method.
Follow the methodology in CIBSE TM59 when using dynamic thermal analysis to predict overheating risk in homes.
Documents related to the consultation on proposed requirements for mitigating the risk of overheating in new dwellings can be found here.
