Collaboration between the architectural and building physics teams ensured that environmental performance informed each stage of the design process. The early application of Passivhaus principles supports high levels of thermal comfort and energy efficiency while maintaining a practical approach to construction and delivery.
A key element of the design is the “second skin” to the east and south-facing façades. Access decks and balconies sit behind prominent brick piers, setting homes back from the road and providing privacy. The piers and balcony overhangs also form an integrated external shading system, reducing direct solar gain to the east façade.
The gable roof gives the building a more suburban residential character, while introducing the challenge of highly exposed roof lights. Although these tilted skylights provide beneficial passive solar gain during winter, they can increase overheating risk in summer. DesignPH, a Passivhaus plug-in for SketchUp, was used to test shading options. This resulted in discreet projecting aluminium canopies, designed to shade each skylight from high angle summer sun without compromising outward views. Similar canopies were incorporated above the south-facing top floor windows to limit peak summer solar gains.
Highly efficient Exhaust Air Heat Pumps (EAHPs) were specified to reduce space heating demand, supported by a roof-mounted photovoltaic array. Energy calculations demonstrated a 33% improvement on the Part L 2021 baseline through fabric efficiency alone. The EAHPs and PV array delivered a further 61% reduction in CO₂ emissions, resulting in an overall 94% saving against the Part L baseline and reducing annual operational emissions by33.4 tonnes of CO₂.
Overheating risk was assessed using thermal dynamic modelling. All sampled flats meet Part O overheating criteria with fully openable windows. Trim cooling integrated within the EAHPs will also help manage peak temperatures where residents may be unable or unwilling to open windows due to noise, security or other external conditions.
