Good Homes Alliance launch overheating in new homes tool
The Good Homes Alliance (GHA) has recently launched a tool which can be used at a very early stage to help designers identify and reduce the risk of overheating in new homes.
Currently, the guidance available in Approved Documents F and L, if applied correctly, should result in well ventilated, energy efficient new homes where heat gains are minimised. However, research by GHA has shown that there are various external and uncontrollable elements that can affect the comfort of people living in these homes, and these elements are sometimes overlooked.
What the tool does
The GHA tool aims to help designers identify factors that can result in overheating and encourages a broader approach to reducing the effects of these issues. It is intended to be used prior to the detailed design stage and ideally before planning submission and approval, as it may be difficult to apply some of the recommended improvements after that point.
The tool can be used to assess either an overall housing scheme or individual dwellings. It takes users through a set of questions, each providing a score which contributes to a total. This total will help the designer to identify whether there is a low, medium or high risk of overheating for the property. For each question there is an explanation of why it is relevant and how to assess the score, as well as examples of issues that can arise and ways of overcoming them where possible.
Issues around overheating
Some of the key factors affecting overheating that are addressed by the questions in the tool are:
- Desirability of opening windows – concerns including security risks, excessive noise, pollution and heat emitted from adjacent properties can reduce the likelihood of occupants opening their windows.
- Communal heating systems – the inability to locally control temperature, as well as the heat generated by hot pipework and its location within less ventilated internal spaces, such as common corridors, can contribute higher temperatures in adjacent dwellings.
- Extent of glazing on east, south and west faces of the building – a higher proportion of glazing can generally result in more heat gain.
- Colour of nearby surfaces – light coloured surfaces are more reflective and can result in lower surface temperatures and lower heat absorption than dark coloured surfaces.
- Thermal mass – properties with high thermal mass can help to absorb heat during the day, however, this must be combined with effective night-time ventilation.
- Viability of ceiling fans – ceiling fans can aid internal air movement.
- External shading – purpose-built external shading devices can significantly reduce solar gain, e.g. shutters, awnings, balconies above.
- Windows – the extent of openable windows and opening area can significantly affect the likelihood of overheating.
Decisions made early enough in the design, informed by GHA’s tool, could contribute to a reduction in the occurrence of overheated homes.
There are several worked examples provided alongside the tool to further assist users in assessing their own projects.
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