Thermal mass in lightweight domestic construction

Thermal mass in lightweight domestic construction

Date Published

6 September 2022

Document Type




High levels of thermal insulation and airtight fabric in modern residential building has raised concerns that recently built dwellings will have a tendency to overheat during periods of hot weather. Concerns that global warming may cause further rise to UK temperatures in the next 50 years (within the lifetime of these dwellings) would only exacerbate this tendency.

Key Information

Lightweight framed construction can deliver cost-effective houses without a significant increased risk of overheating compared to traditional construction. However, future climate changes and increased levels of thermal insulation and airtightness mean that cooling strategies should be considered as part of the design to avoid the need for mechanical cooling.

These strategies could include:

– Secure ventilation – effective, controllable and secure ventilation could be provided through secure openings, stack ventilation systems or even mechanical ventilation. This is of particular importance for night-time comfort.

– Solar shading – this could include overhangs or brise soleil and should be external to the building, enabling the reduction of solar gain.

– Solar control glazing – this can also be used to reduce solar gains through the windows by including a reflective coating on the external side of the glass to reduce solar gains.

– Energy efficient equipment – low energy appliances and lighting can cut down on internal heat gains, thus mitigating overheating risk.

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Case studies

As part of a collaborative design project, Foster + Partners designed the roof and external facades of the overground structure, including the retail facades. The structure is unified by a timber diagrid roof which curves around the building like a protective shell.

Most timber used in buildings today is machined, glued and fabricated, creatingstandard products from what was a very
non-standard element, a tree.