Base heating in the church: how temperature affects the electricity cost

Temperature is the parish's biggest electricity issue

In an electrically heated church, heating accounts for most of the electricity consumption. That makes the temperature strategy the decision that affects the electricity cost most, more than the choice of electricity contract. At the same time, it is a decision that is not only about money. The building, the furnishings and the organ are affected by how the church is heated.

This guide describes how base heating, heating ahead of services and ceremonies, and humidity relate to the electricity cost. It does not replace an assessment by a building conservation officer, conservator or organ builder for your particular church.

Two ways to heat a church

Base heating is the temperature the church maintains when it is not in use. It runs around the clock throughout the heating season and therefore accounts for a large share of consumption.

Temporary heating is when the temperature is raised ahead of a service, baptism, wedding or funeral and then lowered again.

The lower the base heating, the less energy is used during the hours the church stands empty. But the more the church must be heated before each service or ceremony, and the longer it takes.

What the sources say about levels

There is no single temperature that applies to all churches, and the recommendations differ.

• The county administrative boards (länsstyrelser) of Stockholm, Södermanland and Örebro counties state in 2021 guidance that base heating should be kept as low as possible, around 10–13 °C, but not so low that there is a risk of frost, and that the temperature should not exceed 18–20 °C when the church is heated. For churches with sensitive furnishings, a relative humidity of 40–60 percent over the year is given, with as little variation as possible.
• Several parishes in the Diocese (stift) of Skara have gone further. One pastorate lowered the base temperature in most churches to 5 °C and switched off the heating completely in some churches for part of the winter. Another lowered it to around 4 °C and later lower in churches with dehumidifiers. Both controlled humidity instead and reported roughly halved consumption for heating.
• The Swedish National Heritage Board (Riksantikvarieämbetet) has published the report Att sluta värma en kyrka (Stopping heating a church) on what a sharp temperature reduction involves.

The practical advice is the same in all sources: decisions to lower the temperature should be based on measurements and on an assessment of the building and furnishings, not on a figure from another church.

Humidity matters more than temperature

When the temperature is lowered, relative humidity rises. It is humidity, not the cold itself, that creates a risk of mould, cracks in wood and damage to paintings and textiles. Experience from the Diocese of Skara is that problems arose mainly when humidity was not controlled.

Lower base heating is therefore often combined with:

• Temperature and humidity meters that log over time
• Dehumidifiers controlled by humidity instead of raising the heat
• Controls that start the heating only if humidity cannot be kept down in other ways
• Warm storage spaces for sensitive textiles

Dehumidification also uses electricity, but usually much less than heating the entire church interior to lower humidity.

The organ

The organ is often the church's most sensitive furnishing. Rapid changes in temperature and humidity can affect tuning, wood and leather. We have not found a generally applicable source for which levels apply, and organs differ considerably. Consult the organ builder who maintains the instrument before changing base heating or heating times, and ask for recommendations for your particular organ.

The peak load before the service

This is where the temperature strategy meets the grid fee (nätavgift). When a cold church is heated ahead of a funeral on a winter day, all heating runs at full capacity for several hours. The county administrative boards' guidance states that temporary heating can take roughly 6–12 hours.

For a church with a capacity subscription (effektabonnemang), usually when the main fuse is above 63 A, the peak hourly load is decisive. If the measured capacity exceeds the subscribed level, the grid company often charges an overrun fee. A single heating session on a cold day can set the year's peak.

It is often possible to reduce the peak without the church being colder during the service:

• Start heating earlier at lower capacity instead of full capacity in the last hours.
• Avoid heating several buildings at the same time that share the same connection.
• Do not overdo it. A lower target temperature during the service reduces both energy and capacity. A pastorate in the Diocese of Skara lowered it from 21 to 19 °C for services and ceremonies.
• Check the controls. A heating system that switches everything on at once produces a higher peak than one that steps in gradually.

Read more in Peak loads: lower your grid fee and capacity charges for businesses.

Calculate for your own church

Example: A church uses 80,000 kWh per year, of which, in this worked example, 60,000 kWh goes to base heating. If a lower base temperature with controlled dehumidification reduces base heating by a third, 20,000 kWh is saved. With 36.0 öre/kWh in energy tax and an assumed electricity price including markup of 80 öre/kWh, that comes to 20,000 × 1.16 = 23,200 kr per year before VAT and the grid's transmission fee. The dehumidifier's consumption must be deducted.

The figures are examples. The actual effect depends on the building, the heating system and how often the church is used.

Permits and cultural heritage

Church buildings are protected under the Swedish Historic Environment Act (kulturmiljölagen). According to the county administrative boards' guidance, a permit from the county administrative board is required for significant changes, such as installing a new heat source, dehumidifiers or replacing radiators. Changing the settings of existing heating normally requires no permit, but installations for control or dehumidification may. Contact the diocese and the county administrative board early.

What you can do today

• Find out what base temperature is set in each church and who decided it.
• Borrow or buy a temperature and humidity logger and let it run through a winter. Several dioceses lend these out.
• Request hourly values from the grid company and see when the year's highest hour occurred. Was it heating ahead of a service or ceremony?
• Ask the organ builder what changes the instrument can tolerate.
• Raise the temperature strategy with the diocese's building conservation officer or property department before changing anything.

Also read Rarely used churches and chapels and Electricity contracts for churches and parishes.

Savera can calculate how the parish's temperature strategy affects the electricity cost and grid fee, as a basis for decisions together with the diocese.