The 1st October 2015 saw a change in Section 6 of the building standards in Scotland, taking a significant step closer to Zero carbon building.
The requirements for both Domestic and Non-domestic buildings will require an uplift in building standards.
Q. What is Section 6?
Section 6 supports the climate change (Scotland) Act 2009 which aims to reduce carbon emissions by 80% by 2050. This regulation ensures effective measures for the conservation of fuel and power are taken when constructing new or modifying existing buildings.
The changes represent a 21% improvement in Domestic standards and a 43% improvement for Non-domestic buildings against the 2011 standards levels. At MKM the focus will be on Domestic purpose buildings.
New Builds in Scotland
Q. How to comply?
The regulation provides two ways to comply with section 6: via a ‘Calculation Method’ or a ‘Simplified Approach Method’.
Both methods are based on the same notional dwelling specification packages, with the recipe for compliance varying based on main heating fuel. Following these packages’ requirements allows for simplified approach compliance, but some deviation from the packages is possible by adopting the calculation approach.
The two methods are explained below.
The Calculation Method allows flexibility in achieving the Target CO2 Emission Rate (TER) for the ideal, or ‘Notional’ Dwelling. An energy assessment can assist in achieving a Dwelling Emission Rate (DER), less than or equal to the TER, whilst also ensuring certain minimum standards are also bettered.
NB: Unlike in England, Scotland does not require a FEES score.
Simplified Approach Method
In this method, the dwelling must comply with the package specification used to set the notional target level, based on the type of fuel used for the main heating system. There are five packages outlined detailing: the criteria for the fabric heat loss, building services and air infiltration, view details for the five packages here.
The simplified approach insulation requirements are consistent for a new build, it is only the building services that alter.
Following this approach should achieve the CO2 emissions level set in the calculation methodology.
For the best chance of compliance, thermal bridging must be addressed, suggested details can be found within the ‘Accredited Construction Details (Scotland) 2015’ which if followed should achieve the performance levels required by the simplified approach.
If no attention is paid to detailing then the default y-value of 0.15 will be difficult to compensate for, due to the more stringent requirements on emissions required elsewhere in the design.
NB: For Non-Domestic regulations refer to the Scottish Government’s website gov.scot/.
Extensions in Scotland
As outlined in the customer guide, extensions can follow an elemental approach.
In Scotland the requirements are different to England’s. Whilst the approach remains elemental there are two rules to follow depending on the type of dwelling.
Where U values for wall and roof of the existing dwelling are poorer than 0.7 and 0.25 respectively the builder must follow the below prescribed values:
Where parameters for the first rule do not apply (insulation properties are better) the below U values are to be met:
There is also an alternative approach that can be adopted, particularly where extensions are highly glazed allowing for a compensatory approach to be followed – this can either involve an area weighted U-value trade-off, or a more complicated whole dwelling approach where the dwelling and it’s extension can be modelled by an energy assessor.