New Building Regulations on energy conservation (Part L) published in March are to demand a flat rate approach to the 25% carbon emission reduction. This means every home being built must achieve the new level, instead of an aggregate approach – the level being achieved across all new homes as an average. “This flat rate is going to be challenging for midterrace and mid-floor apartments,” HBF technical director Dave Mitchell said. He also explained that the accompanying SAP software was going to require housebuilders to insulate party walls before considering the 25% improvement. “This was a surprise – we hoped that party walls would be part of the 25%. Again, this will be harder for mid-terrace and mid-floor apartments, and overall more expensive.” Changes to Part L, and Part F on ventilation, come into effect in October. <br>