The whats, whys and hows

Understanding how to calculate heat loss is a crucial part of designing and installing efficient heating systems, especially given the rise of boiler alternatives. Here, Ian Trott, training manager at Baxi, looks at how heat-loss calculations help to determine the appropriate size of equipment needed to maintain a comfortable temperature in a building while minimising energy costs, whatever the heat source.

Over the past several years, and especially over the previous 12 months, it has become overwhelmingly clear that energy efficiency needs to be a major priority. This goes for governments and industries as much as in our homes. Heating installers have a crucial role to play not only in installing a heat pump or boiler but in being heating experts.

It’s important to understand this evolving role in the race to net zero and that, no matter the appliance being installed, you can promote efficiency at every opportunity. It’s time to rethink your role as a professional who fits boilers as someone who is also a heating and energy consultant, recommending efficient solutions based on the household’s requirements and scientific principles.

When advising consumers on how to improve their home’s energy efficiency, you need a firm grasp on heat-loss calculations and be ready to discuss them with your customers.

generally use more energy to heat up and so produce more than is needed for the space. Along with the cost of the energy output, bigger units are more expensive to install and maintain. If a large unit is installed in a building that only needs a relatively small boiler, the oversized appliance will not be able to run at a peak performance, which means that more maintenance will be needed, further adding to costs.

By making heat-loss calculations part of every heating installation – as required by Part L of the Building Regulations – it will be possible to recommend a heating solution that strikes the right balance between being powerful enough to meet peak demand for heat and being efficient enough to keep costs and emissions down.

How to gather information for heat-loss calculations

Part of the calculation process involves understanding and anticipating your customer’s heating needs, so talking to

Why are heat-loss calculations needed?

Heat-loss calculations balance the amount of energy needed to overcome the heat lost though the fabric of the building. Although some might expect a larger heating system to provide the extra assurance that output will always meet peak demand, a heating system that is too big for the building can be counterproductive.

An oversized heating system is less efficient because it will them is an important part of the process. Ask about their current heat use, and whether they expect it to change so that you can make an accurate estimate. Questions about changes to the property, such as plans to have double-glazing installed, or to convert the loft into a home office, can give a clearer picture of what the heating system will be required to do.

Changes to the residents can be relevant, too. Will children or older people also live there in the future? The heating requirements for an older person can be different from someone in their 20s or 30s, so anticipating these changes makes it more likely that the proposed heating solution will meet the household’s needs.

The next stage is to assess the building. This includes measuring its overall size as well as the size of each individual room. Measuring every room in the