Improve energy efficiency

Improved church insulation reduces heat losses and increases energy savings. However, there are other methods of reducing heating costs.

Use your church as a thermal store

Infrared heaters produce an electromagnetic wave that energises and warms thermal mass directly, for example a building’s structure. The infrared rays are mainly absorbed by the walls and floor which then serve as a storage medium and gradually release heat back into the church.

The energy produced by an infrared heater is retained within the thermal mass of a building for a significantly longer period than the heat produced by a convection heater. Air is a very poor thermal store! Retaining energy within the church for longer means that less energy is required to maintain the ambient temperature.

People are directly warmed by infrared
Medium-wave infrared puts energy into the walls and floor which is released as warmth into the church

Reduce temperature gradient

Warm air is lighter than cold air and is gathered in the highest spot inside a building. Vertical temperature differences between floor and ceiling occur. In rooms with high ceilings, like a church, the temperature difference between the dwelling zone and the ceiling is typically between 5 to 8°C. Equalizing the temperature differences can reduce heat losses by as much as 20% while making optimal use of the heat.

A church with high ceilings using infrared heating reduces the vertical temperature gradient between floor and ceiling. The heat develops when the rays meet surfaces such as floors and walls. The surfaces in turn heat the air in the dwelling zone. The temperature differences between the ceiling and the floor become very small and overheating is minimal.

Temperature gradients from infrared and convector heaters

The temperature gradient (temperature rise per metre of height) is very low for infrared heaters: approximately 0.3°C/m. In contrast, warm air heating or heating with conventional radiators causes significantly greater temperature differences per metre of height with temperature gradients of 2.5 and 1.7 °C/m respectively.

In buildings with high ceilings, substantial energy savings are obtained compared to conventional heating systems, where most of the energy is used to overheat the space above the dwelling zone.

Lower indoor temperature

Because of the direct heating effect of infrared heaters, the air temperature can be lowered by a few degrees (from 21°C to 18°C) without sacrificing comfort. For every degree the temperature is lowered, an energy saving of around 6% is realised.

Heat loss in churches

Energy losses in a church can be divided into two categories:

  • Transmission losses via building structures (roof, walls, etc.)
  • Ventilation losses through ventilation, leakage and openings
Church heat loss by transmission and ventilation

The size of transmission losses varies according to the areas of the building parts and insulation. The losses are proportional to the temperature differences between indoor and outdoor air.

Ventilation losses in a church are either mechanical or natural/involuntary. Mechanical ventilation usually consists of a supply and exhaust air unit that makes heat reclamation possible. Natural and involuntary ventilation consists of thermal currents causing warm air to rise and leak through openings and unsealed areas.

Types of church heating system

Within church areas with high ceilings, the heating system must cover all energy losses, both from transmission and ventilation. Three main types of heating are used in the UK:

  • Infrared heating – transfers heat to surfaces and objects without warming the air on the way. Surfaces are heated and then in turn heat the air within the room. People experience the direct effect of infrared heat as warmth. The space feels comfortably heated, even if the air temperature is relatively low. Infrared heating also prevents overheated air gathering under the ceiling. The minimal temperature gradient between floor and ceiling, as well as the lower air temperature, contributes to large energy savings. Infrared heat effectively counteracts cold radiation and cold draughts, for example from large windows and ill-fitting doors.
  • Air heating – uses warm air to cover heat losses from the building. The warm air cools along the outer walls, due to transmission losses. Therefore, the supply air temperature must be higher than the desired room temperature. As the heated air is lighter and rises in the church, large temperature differences occur between the ceiling and the floor. At times, it may be necessary to equalise the differences with ceiling fans.
  • Convective heating – transfers heat to the room by warming the air as it passes the hot surface of a radiator or convector. The air-flow past the radiator or convector is maintained by convection currents. The warmed air rises and is constantly replaced by cooler air. For example, cold draughts from windows are counteracted by rising warm air if the heat source is placed under the window, as is traditionally the case.