Heating for the building#
Until recently, the conventional wisdom has been to choose a minimum temperature for the building based on its construction and its contents and avoid going below that temperature. For modern buildings, the architect’s intended temperature might be specified on the architectural drawings but there could be a “better safe than sorry” element to this, especially if the drawing is from an era of cheap energy. For older buildings, the minimal requirement appears to be keeping the building at a high enough temperature to guarantee it will stay above dewpoint, to avoid condensation. Under UK conditions sometimes the advice is to enforce 7-8C as a bare minimum for this reason. What your building needs could be higher, depending on its construction and also what it contains.
If you have a massive stone building that is frequently occupied and heated, the risk of it getting very cold is low. Stone warms up and releases heat slowly. For buildings with lighter weight construction or in less use, your insurer may require you to enforce a minimum temperature in the building. This is a very safe approach to preserving the building and its contents, it just may be more energy-intensive than is necessary. For instance, many of our churches survived just fine without any heating for centuries. Conservation experts are currently discussing this and some are issuing new advice not to worry about the minimum temperature, but to make sure the building is well-ventilated.
You should discuss whether your venue enforces minimum temperatures and whether those minimum temperatures are appropriate, taking advice from your architect if required.
Minimum temperatures and stone buildings
For massive stone buildings that are heated for occasional events, there can be a benefit to enforcing a setback temperature: thermal comfort. Consider two ways of using the same amount of gas. The first leaves the building cold most of the time, whacking on the heating to bring up the air temperature when people will be in. This is what most building operators do. The second takes the same energy, but applies some of it to enforce a setback temperature that will make the walls warmer, and the rest to raise the air temperature when people are in, but more modestly. The bigger the difference between the air temperature inside and outside the building, the faster the heat loss. In the second case, the building will retain more of the heat, and could be as comfortable - because the internal surfaces are a bit warmer, and because it will have fewer draughts. It will also be noticeably more comfortable for people who are in the building at odd times, and better for any delicate artefacts in the building, like organs, as they prefer gentle changes. Higher occupancy rates make it easier to make use of this benefit.
Pipe organs
Churches often think that pipe organs need warmth, but cold doesn’t bother them. They don’t like fast temperature variations, and they can sound out of tune unless they are tuned at the same temperature that they are played. They also care very much about being too dry, and somewhat about being too damp. 55-75% RH is the ideal range.
Think about how to make your pipe organ happy, but this doesn’t necessarily mean running the heating.