While energy efficient boilers have been passed over by the Green Homes Grant in favour of low-carbon alternatives, it's possible to make your heating eco-friendlier while sticking with a boiler system. 

  boiler controls - eco-friendly boiler guide - grand designs

Image: Boiler Guide

The government’s Green Homes Grants scheme is offering up to £5,000 to homeowners in England who want to carry out energy-saving improvements on their property. A large chunk of the country’s carbon emissions come from the gas and oil-fired boilers we use to heat our homes, so in addition to improving insulation, the grants can also be used to install renewable heating technology like a heat pump, solar thermal panels or a biomass boiler.

However, some homeowners may not be willing or able to leave their familiar boiler behind, but still want to make their home a little greener. David Holmes of Boiler Guide explains how homeowners can make their heating eco-friendlier while retaining the familiarity of a boiler system.

Upgrade to a condensing boiler

If your boiler was installed before 2005, it may operate using non-condensing technology, which means it could be wasting 30-50% of the fuel it uses. This is not only bad for the environment as carbon emissions will be high, but will also be leading to high heating bills. A condensing boiler is able to capture and recycle heat which would otherwise be lost and redirect it so it can be used again. This leads to reduced carbon emissions and lower heating bills. In 2005, it became illegal to install a non-condensing boiler.

When you install a new boiler today (October 2020), by law it must use condensing technology and (thanks to Boiler Plus legislation in 2018) must achieve a minimum efficiency of 92%, so it only wastes up to 8% of its fuel. In addition, all new boiler installations must include operational time and temperature controls, and combi boilers must have one of the following additional energy-saving features:

  • Load compensation which modulates the flow temperature from the boiler based on the actual room temperature, this requires the control and boiler to be able to communicate.
  • Weather compensation, i.e. the ability to modulate the flow temperature from the boiler based on the outdoor temperature.
  • Smart controls that provide automation and optimisation (more information below).
  • PFGHRD (Passive Flue Gas Heat Recovery Device).

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Switch to a new type of heating system 

If your boiler requires a hot water cylinder to be able to produce hot water for your taps and shower, you may be able to reduce energy consumption by changing to a combination boiler. The first step is to understand the type of heating system you have now.

If you have a boiler, a hot water cylinder in an airing cupboard, and a large tank of cold water in the attic, you have a regular boiler. If you have a boiler and a hot water cylinder but no tank in the attic, you have a system boiler.

 In both scenarios, your boiler produces hot water for the central heating, and sends it to the cylinder so it can be stored until it is needed. While the water is waiting to be used, it is losing heat, particularly if the cylinder is not well-insulated. The cylinder may also include an electric immersion heater which can top up the heat, and this can be costly to power and increases the property’s carbon footprint.

Read more: Easy tips to improve your home's energy efficiency

Your first option is to take steps to insulate the cylinder with lagging, or you could upgrade to a more energy-efficient cylinder, but some properties may be better served by switching to a combination or combi boiler.

A combi boiler is a compact all-in-one unit which takes its cold water supply directly from the mains (resulting in a higher water pressure) and heats water on demand. This means that a hot water cylinder is not required, hot water is not sitting around losing heat, and you only heat as much water as you need to use. While most new boiler installations in the UK are combi boilers, it is important to note that they are not always suited to large homes with multiple bathrooms as they struggle to supply lots of outlets at the same time.

 Wiser Google Home smart thermostat - eco-friendly boiler guide - grand designs

Image: The Wiser smart room thermostat from Drayton Controls is compatible with smart voice assistants. 

Install smarter heating controls

Heating controls have moved on significantly in recent years, and having greater awareness and control of your heating usage is a key part of improving energy efficiency.

Smart meters enable you to keep track of exactly how much energy you are using by the hour. This makes it much easier to identify when and where in the home you are using the most energy and make changes to your routine accordingly.

 Smart thermostats are connected to the WiFi and enable you to control your heating (either via a schedule or in real-time) via an app on a smart device from wherever you are in the world. This means you never again need to heat an empty home, i.e. you can turn the heating off when you are late home from work, or you have a sudden change of plans. Many smart thermostats also feature GPS tracking and motion sensors so they can turn on/off automatically depending on who is in the home. Some will also learn your routine, build a schedule around your habits, and provide regular reports on your energy consumption.

Another option is to install smart TRVs (thermostatic radiator valves) which are fitted to radiators in your home. You can then control the heat in your home on a room-by-room basis or by separating the upstairs and downstairs into zones. This means you can heat rooms to different temperatures depending on your preferences (e.g. keeping the bedroom cooler and the bathroom warmer) and can avoid heating rooms which are rarely used.

solar thermal panels on roof - eco-friendly boiler ideas - grand designs

Image: Boiler Guide

Install solar thermal panels with your gas boiler

If your boiler was installed relatively recently, but you want to make the system eco-friendlier, consider installing solar thermal panels which will work alongside the boiler. Solar thermal panels are fitted to the roof where they are exposed to sunlight, and can use the sun’s energy to heat water for a hot water cylinder.

While solar thermal panels are unlikely to produce enough hot water for all your needs, they will reduce the amount of work your gas boiler needs to do, easing the strain on your boiler, reducing your carbon footprint and your heating costs. This option is not suitable for homes with combi boilers as a hot water cylinder is required.

Solar thermal panels are eligible for the Green Homes Grant scheme.

Install a biomass boiler

A biomass boiler is fueled by wood pellets, wood chips, or logs. Biomass boilers are physically larger than gas boilers as they need to be able to accommodate the physical fuel, and they need to be fed the fuel manually. They also require a hot water cylinder as the hot water produced needs to be stored.

Biomass boilers are regarded as carbon neutral, as they are fueled by wood. When the wood is burned, it only emits as much carbon as it absorbed while the tree was growing, so no additional carbon enters the atmosphere when the boiler is working.

Biomass boilers are also eligible for the Green Homes Grant scheme.

Read more: Green Homes Grant: a guide to biomass boilers


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