Heating

Heating typically accounts for about half of the energy used in offices and forms a significant proportion of energy use in other areas of a business. It is a key area to target with energy saving measures. Many businesses are overheated which can cause discomfort and wastes money.

This guide discusses key areas and quick wins to improving the efficiency of your existing heating system. It provides advice on reducing the need for heating by preventing heat escaping from your building, the options for heating and control systems, appropriate renewable heating energy and advice on financing heating upgrades.  

‘Fabric first’ approach to reducing heating bills

Taking a ‘fabric first’ approach is an effective way to reduce the amount of energy used for heating. This means first making sure that the fabric of the building – the walls, floors, roofs, windows and doors – is insulated as thoroughly as possible to minimise heat losses and reduce the demand for heating energy. The next step is to ensure that the building services, in this case the heating system and its controls, are as efficient as possible. Finally, once the overall energy demand is as low as possible, the final step is to choose a low carbon energy supply.

‘Fabric first’ approach for energy efficient heating:

1. reduce energy demand by improving the building fabric (walls, floors, roofs, windows)
2. meet energy demand efficiently by improving the heating system and controls
3. supply energy from low carbon sources using renewable energy technology

Avoiding heat loss

• Is the building well insulated?

A good starting point for improving building fabric is to look around a building and create a checklist of areas to inspect regularly and problems to look out for. Check roofs and lofts, walls, windows and doors which can offer low or no cost efficiency measures. Installing loft insulation in an uninsulated pitched roof is likely to be the single most cost-effective way to improve the efficiency of building fabric and save money on heating. It is also possible to upgrade existing insulation on the majority of roofs by adding to what is already there (providing it is in good condition and not damp). If there is less than 15cm (6 inches) of insulation, it is always worth adding more.

• Are windows and doors left open during the heating season?

Open windows during the heating season indicate poor heating control. Instead of opening windows to cool the room, turn down thermostats a little until a comfortable temperature is reached. Use promotional material and staff meetings to ensure that employees are aware of how to report overheating and how the heating is controlled. Advice on employee engagement and informative stickers and posters are available from the Energy Saving Trust’s website.

• Are there cold draughts coming from windows and doors?

Draughts are not only a cause of complaints and discomfort, but waste money. A door with a 3mm gap will let in as much cold air as a hole in the wall the size of a brick. When a building is draught-free, its heating systems don’t have to work so hard. Draught proofing is a cheap and effective way of saving energy and improving thermal comfort within a building. 

There are a range of different draught proofing options and costs, including rubber seals, brush strips and compressed seals. Draught proofing a small commercial building is a low cost measure that should be recovered within five years and, meanwhile, people in the building will be warmer and more comfortable. 

• Is the building dry?

Wet buildings are harder and more expensive to heat than dry buildings, and excessive moisture can result in expensive structural damage as well as create an unpleasant, and potentially unhealthy, working environment for occupants.

It is important to carry out regular building checks, to ensure gutters and drains are clear, and that the roof and fabric of the building is sound. It is particularly important to carry out these types of checks before the winter season. Catching a problem early is almost always cheaper and easier to rectify.

Equipment and heat usage

• When were the heaters or boilers last serviced?

Heating costs can increase by 30 per cent or more if the boiler is poorly operated or maintained. Ensure they are serviced at least annually and adjusted for optimum efficiency.

• Are the radiators working effectively?

Excess air in conventional radiators will stop them warming up, so it’s wise to ‘bleed’ them occasionally to stop air build-up. You’ll know if your radiator needs bleeding if it feels warm at the bottom and cold at the top. Here’s how to do it:

• turn the heating off and let the system cool down completely
• use a radiator key to slowly turn the bleed valve (this will usually be at the top and on one side of the radiator) until you hear air escaping
• hold a cloth underneath to catch any moisture that drips out
• bleed the radiator until you can hear no more air escaping and a droplet of water appears, as soon as this happens quickly tighten the valve

• Is there evidence of use of portable heaters?

Portable electric heaters are expensive to run. A 2kW heater costs around 20p per hour to operate. Running for eight hours a day each heater would use £8 per week or over £120 per year.

Portable heaters can affect the general temperature control of the space you are trying to heat. If there is a genuine need for them there is likely to be a problem with your heating system or building fabric. If it is not possible fix the problem, make sure supplementary heating is correctly installed and operated. Utilise timer controls where available to make sure heaters power down out of hours or raise awareness to turn them off.

Any portable heaters in the workplace should be subject to PAT testing which enables the policing of their use. Unlabelled items can then be removed and ‘illicit’ use can be restricted. 

• How is the hot water provided?

Hot water is often run continuously and temperature settings are often set too high so energy use associated with hot water can typically be reduced by 20 per cent. To make energy savings in this area, set hot water temperatures to 60°C and not below (due to the risk of legionnaires).

Another option is to consider installing local instantaneous water heaters where small quantities of hot water are required a long way from the main heating plant. This may also allow the main boiler to be switched off in the summer.

Finally, ensure that you insulate all hot water tanks, boilers, valves and pipework unless they provide useful heat to occupied spaces. 

• How efficient are your hot water taps and showers?

Reducing the flow rate of hand basin taps and showers will not only reduce overall water consumption but help to cut down on the amount of energy needed to heat hot water. 

Tap aerators and flow restrictors are low-cost solutions which can reduce water use by up to 70 per cent. A flow rate of 5-6 litres per minute is adequate for hand washing, and 8-10 litres per minute is adequate for showering.

Current flow rates can be calculated by using a flow meter or a stopwatch to record the length of time it takes to fill a 10 litre bucket with water. For example, if it takes 90 seconds to fill the 10 litre container, you can work out the flow rate (litres per minute) as follows:

• 10 litres / 90 seconds = 0.11111 litres per second  
• 0.11111 litres per second x 60 seconds = 6.66 litres per minute

• Do all areas have the same heating requirements?

Consider heating your building in zones to allow heating to be adjusted for each area. Areas such as storerooms and corridors, or areas where there is a high level of physical activity, require less heat.

Warehouses are sometimes heated in an attempt to reduce humidity and maintain product quality, but warm air can often hold more moisture than cold air and heating may actually increase humidity. Dehumidification can be more efficient for this purpose.

Additionally, remember the effect of sunlight, consider whether you are heating areas that are already warmed by the sun.

Controls and timing

• Are thermostats correctly set?

Heating costs rise by about 8 per cent for every 1°C of overheating. Ensure thermostat settings are in accordance with Chartered Institute of Building Services Engineers (CIBSE) guidance:

• Heavy activity: 11 - 14°C
• Light activity: 16 - 19 °C
• Sedentary: 19 - 21 °C
• Offices: 21 – 23 °C

Install thermostatic radiator valves where possible to provide local control of radiators and make sure they are used correctly.

Ensure that thermostats are placed in the correct locations away from draughts and direct sunlight and at a distance from any heating sources.

Zone controls also allow heating or cooling of different parts of a building at different times and different temperatures according to occupants’ needs.

• Are you a Retailer? 

If so, also consider outside temperatures. Customers will be wearing warmer clothing if it is cold outside, so in-store temperatures should be set so they do not become uncomfortably hot while in-store. Some retailers waste energy by heating the area to accommodate staff wearing short sleeved uniforms. Always provide practical staff uniforms so appropriate, comfortable temperatures can be maintained.

• Are there heaters and air conditioning units operating simultaneously in the same space?

Simultaneous heating and cooling of a space is commonplace and wastes a lot of money. Set a ‘dead band’ of 4 - 5°C between heating and cooling, to avoid this happening. For example, ensure heating systems only come on when temperature falls below 19°C and cooling systems only come on when the temperature rises above 24°C to avoid heating and cooling systems working against each other. This can save up to 20 per cent of heating and cooling energy. 

• Are time controls correctly set?

Does your heating come on only when needed or is it heating the building when no one is there? Heating your premises when it is empty wears out your boiler and increases costs of heating. Your building will hold on to heat for around one hour after it is turned off, so switch off the heating earlier than the time that you expect to leave. 

Use simple time switches or seven-day timers to help to automate the process so that nobody forgets to turn off the heating when it is not needed. Ensure time settings are reviewed at least every month (if not more regularly) to check that they are appropriate.

Many systems function inefficiently because of short term adjustments which are forgotten about, so ideally have at least one designated person who controls the heating system. Additionally, do not rely on a third party to manage your schedules and if necessary ask them to instruct you in the use of the controls. 

• How are extract fans, for example in toilets, controlled?

Fans left running extract warm air and waste money – consider fitting time switches or occupancy detectors.

Replacing your heating system

If your existing boiler or heater is over 10 years old, you may look to replace it with either an efficient like-for-like model or an entirely different system altogether. A good place to go to find the most efficient products on the market is the Energy Technology List (ETL). 

Renewables
If you are looking to move to a renewable heating system,  the technologies that you may like to consider are:

• Heat pumps
• Solar thermal panels
• Biomass 
• Combined heat and power (CHP) systems

Further information on renewables can be on Carbon Trust website and the most efficient models can also be found on the ETL.

If you are looking to replace your heating system, it is strongly advised that you seek professional support to scope out the correct solution for your needs. If you are struggling to find a reputable supplier, you can use the Carbon Trust’s Green Business Directory - more information in the following section.