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Not-in-time heating

Not-in-time heating is a very common pattern in community buildings. We describe some common reasons for it.

One of our venues is suffering from what we call “not-in-time” space heating. This is very common in community buildings. As you can see from the trace, spaces are cold when people enter, and still pretty cold when they leave. In this venue, which has space heating from a gas boiler, at least the heating doesn’t continue after people leave, but the group isn’t getting the benefit they should from the energy they’re putting in.

There are lots of possible reasons for this, and they’re mostly about the heating controls. Here are the most common ones:

  • The timeswitch doesn’t have optimised start control (OSC). With OSC, the system learns over time to get the heating to the right temperature “just in time”. Without it, the operator has to guess when to turn the heating on and off and reset the heating at least once per season, if not by weather forecast week by week. They often under- or ever-estimate.
  • The clock on the timeswitch is wrong. They drift over time and sometimes haven’t been reset in years. It’s easy not to notice this even if you set the heating every week.
  • The timeswitch is so old it doesn’t handle summer time and it was last set in the summer.
  • The building relies on users turning on the heating from scratch themselves. This can be a good strategy in buildings that are well enough insulated and used that they don’t get too cold, if the system is fairly responsive, but not otherwise.

In this case, we aren’t sure whether the problem is that the timeswitch doesn’t have OSC or the users are left to turn the heating on themselves, but the engineer with boots on the ground will be able to tell. The diary shown is just a typical week, but if the other rises aren’t just atypical room hires, the group might also want to think about what users can do for themselves and, for instance, whether they can turn the heating on for longer than they need.

In a space that retains heat well, better user conditions might take little or no extra energy. This space cools off so fast that using optimised start control to get the building warm in time for groups will cost a fair bit more. Of course, better heating might also make the space more attractive for those looking for a venue.

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