02 Aug

Heatmap of the Month – building fabric vs building systems

As we move into heating season, this months’ heatmaps look at separating the impact of a building’s fabric from building systems when looking at its ability to maintain a stable and comfortable environment.

We’re looking at one floor of a large office building in South London, instrumented with nearly 40 sensors. The building is more than 20 years old, with large expanses of glazing, and as one of the taller structures in the area the upper floors are subject to a lot of solar gain.

This shows particularly clearly in August. Here is one 24 hour cycle (from 10pm Thursday to 10pm Friday) from mid August: over a warm night the building does not lose much heat. Pre-occupation cooling comes on around 6am but as the sun hits the office (on the left hand side of the image) it rapidly overwhelms the capacity of the cooling system. It tracks around the building during the working day leaving behind overheated space.

In contrast, now we have moved into the heating season, the building still suffers some overheating problems but in a pattern that suggests more problems with the building systems rather than fabric. This heatmap shows a 24 hour cycle from 10pm Mon to 10pm Tues. One end of the floor behaves exactly as expected but the other end is warm overnight and during the working day become quite uncomfortably hot.

Graphing the data here shows an interesting feature: overnight in August the office floor cools at the same rate, with a variation of around 2° between warmest and coolest areas.

For October, the variation is much wider – approaching 5°. Overall this is suggestive of some portion of the heating system operating overnight.

If you have got some worries about the temperature in your building, we can help you start to identify the likely causes. Get in touch with your challenge and we’ll help shed some light.