SAP2012 was unveiled under a cloak of darkness and without fanfare at the start of June. Until Part L is confirmed and released in England and Wales (and the updated Section 6 in Scotland), the SAP methodology will not be used, so we’ve got a few months to understand what’s changed, and how that may impact next year’s building projects.
Over this series of blogs, we’ll look at SAP2012 in detail. First up is Ventilation:
Ventilation Systems and Wind Speed
The key change in this section of the methodology is the introduction of localized wind speed data. This will alter the expected air change rate of a building, which will impact the amount of heat loss from a building, and ultimately affect the Dwelling Emission Rate.
Regions which are seen to have higher wind speeds will see the air change rate increase, meaning more energy is required to keep the house heated to a constant temperature.
But, on the flip-side, homes in regions which are seen to have lower than average gusts will be less affected by this, which could lead to slightly better EPC ratings depending on where your site is.
Those areas which will have a higher heat loss due to higher wind speed data include all of Scotland and north England, mid-Wales, Devon and Cornwall.
Below average areas include London, south England, Anglia and the Midlands.
You may think this would make it beneficial for homes in windier areas to install wind turbines, but the new regional data isn’t being applied to this section of SAP – this means a turbine will be measured against a constant wind speed regardless of the region you’re building in.
Semi-Rigid Ducts Introduced
Elsewhere in the ventilation section, whole house systems which use semi-rigid ducts are being introduced into the assessment for the first time. The new SAP methodology says:
“Semi-rigid duct systems... have demonstrated that their performance... is at least equal in terms of aerodynamic performance to SAP performance data for rigid ducts”
This means a whole house ventilation system with semi-rigid ducts will give you a SAP and EPC rating the same as a fully rigid system. Flexible ducting performs worse in the SAP assessment.
The next blog will look at the changes to Party Walls... For daily updates on the changes to SAP and Part L 2013 follow us on Twitter @EnergistUK