Overheating Analysis
Overheat Study
Overheating
Overheating is a becoming more of a problem in building design. As we use ever more insulated buildings with tightly controlled ventilation there is an increased risk of discomfort particularly in the summer months or night time in bedrooms.
The industry has developed guidance such as CIBSE TM52 (“The Limits of Thermal Comfort: Avoiding Overheating in European Buildings 2013”), CIBSE KS16 (“How to manage overheating in Buildings”) and CIBSE TM49 (Future weather data) and Building Bulletin 101 (“Guidelines on ventilation, thermal comfort and indoor air quality in schools”).
Overheating is a measure of:
- Number of hours in a particular room that is occupied that exceeds a likely “comfort temperature”
- Severity of overheating- i.e. a measure of the temperature rise and duration
- An absolute maximum temperature within a given daily period
In simple terms, a good test is to think “how comfortable would it be to sleep in that bedroom on a hot summer day …”!
Overheating Study
Overheating is a measure of how you may feel (“operative comfort”) in your building. Thermal comfort is complex and dynamic (constantly changing), thus it makes sense to use a dynamic simulation model to predict the all the factors. The basic physical factors are air temperature; radiant temperature; humidity and air movement. We also model users (assumptions on clothing and activity) and their behaviour (for example they may open a window or draw down a shade or blind).
Although it is difficult to give a precise risk at a particular time as the phenomenon is inherently imprecise, by looking at the factors in detail we can give an good statistical indication of risk of a particular room overheating.
This allows choices about reflective glass, blinds and which windows to be fixed or openable a more scientific basis in the design process. It’s all part of having a healthy home.
See also this case study.
