Does night reduction with underfloor heating pay off?

There have been some confusing statements from the energy saving trust, as well as some energy companies and installers in relation to heat reduction with underfloor heating systems at night. As this does not reconcile with theory, we will set the record straight in this article.

The heat loss to the outside is proportional to the difference between the average indoor and outdoor temperature. Therefore a study has been conducted to verify the situation in practice. It shows that indeed it pays off to set the temparatur lower as night reduction.

Arguments against night reduction are that it would cost extra energy to heat up the floor in the morning after the cooling of during the night. The more inefficient operation of an HR-boiler would cost relatively more energy. 

However, there is a linear relationship between the gas consumption and the outside temperature, because the heat loss to the outside is proportional to the difference between indoor and outdoor temperature. By measuring e daily gas consumption over a given period and comparing them with the outside temperature in a chart, you can relate the gas consumption as a function of the outdoor temperature record. 

(image by: Photographer Stirling)

From the measurements and derived charts it shows that despite popular opinion of some specialist trade it makes sense to set the themostat bach a few degrees. At Incognito Underfloor Heating Glasgow we advise to lower the thermostat 4 degrees celsius at 9PM. There will still be so much heat in the floor, that the temperature around 11PM will only have dropped about 0.1 – 0.2 degrees. Depending on the outdoor temperature in the course of the night the temperature drops a further 1 to 2 degrees. Usually the heating turn on again at around 7AM or at cold nights at 6.00AM. The achieved savings will then be approximately 14%. After all, the average room temperature descends through the night reduction, so mther is also less heat loss to the outside. 

The heating up in the morning is allowed to be moderate because of increased activity of the household, so high temperature is needed. In the evening however, a slightly higher temperature is pleasant.