Homes in Climate Zone 1 are exempt from the requirement for all window frames to be thermally broken, provided the home incorporates a commissioned whole-house continuous ventilation system. This must include either through-the-wall air vents to support continuous extract ventilation or mechanical supply air to all habitable rooms in a balanced ventilation system. The home must achieve the point in HC3 for ventilation commissioning. Please note that any change to the window frame specification is likely to affect the overall window R-value and must be accurately reflected in any energy modelling submitted for Homestar.