Building regulations upcoming changes to Part L, taking effect on the 1st November 2019 seems to be raising a few eyebrows. For new dwelling’s we are now looking at the NZEB standard. There has been some tweaking of the U-values and ventilation rates but in the main still close to the 2017 standard.
On the plus side is the change in approach to the Renewable requirement, which now sets a ratio of 0.2 or 20 % of the primary energy been from renewable energy, which is calculated using the new DEAP 4.2 software. Previously the requirement was a set amount of 10 kWh/m2/annum (or 4 kWh/m2/annum of electrical energy). These figures where very difficult to achieve and may have caused some over design and costs.
Jury is out on the Major renovation requirement which means improving energy performance to a B2 rating if you are renovating 25% of the building envelope (dry-lining or external wall insulation for example). This will mean a bit more consideration and doing your sums beforehand as you may also have to allow for replacing an older oil boiler and heating controls. A before works BER will help establish what’s required.