Ask most owners of an indoor pool what it costs to run and you get a shrug and a guess. That is not carelessness. It is because the pool sits on the same supply as the house, so there is no number to look at — just a bill that is larger than it used to be.
It is usually the biggest single load on a domestic supply, and it is almost always the least controlled.
Where the money actually goes
Heat loss from the water surface. Evaporation dominates. An uncovered pool loses heat continuously, and the energy required to replace it is the largest line in most plant rooms. This is why the cover matters more than the boiler.
Circulation. Pump power rises steeply with speed, so a pump running flat out for six hours uses far more than one running gently for twelve to achieve the same turnover. A great many domestic pools are doing the former.
Dehumidification. Necessary, frequently oversized, and often running against the ventilation rather than with it.
Air heating. The hall itself, which on a glazed pool room is a serious load in its own right.
Four things, on four separate controllers, none of which can see each other.
The cover is the whole argument
If you take one thing from this: the cover, closed automatically, is the cheapest improvement available and usually the largest.
Relying on somebody to remember it is not a control strategy. Somebody swims at nine, goes to bed at eleven, and the pool spends nine hours evaporating into a room that then has to be dehumidified — paying for the same energy twice.
Automating the cover so it closes when nobody is swimming removes the single biggest variable in the running cost, and it does not depend on anyone changing their habits.
Measure before you spend anything
We would not recommend touching the plant until the loads are separated.
Circuit-level monitoring on the pump, the heat source and the dehumidification tells you which of the four is actually costing you. It is routinely not the one people assume, and it changes what is worth doing. Spending money on a plant upgrade without knowing that is how people end up with an efficient version of the wrong thing.
Once the numbers exist, the decisions get easy: schedule the pump properly, shift water heating to a cheap-rate window or surplus solar, and stop the heater fighting a cover that is already open.
The part that isn’t about money
Humidity is what damages the building.
A pool hall held at the wrong dew point drives condensation into the structure, the glazing reveals and the decoration, and it is usually well advanced by the time anyone notices staining. Continuous humidity and temperature logging, tied to dehumidification and ventilation, is the cheapest insurance on a room that cost a great deal to build.
That is the argument for control that has nothing to do with the bill, and in our view it is the stronger one.
What we do and do not do
We control plant. We are not pool engineers: water chemistry, filtration sizing and the safety compliance of a cover or enclosure stay with your pool company, and where a cover is automated we work strictly to the manufacturer’s interlock requirements and leave the manual override in place.
If your existing plant controller works well, we will often integrate with it rather than replace it, and we will tell you which of the two is better value on the day.
Jack Jones
Director, Westgate Property Solutions · Loxone Silver Partner