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As a result of the Future Buildings Standard consultation, non-domestic buildings will have to be designed to be highly efficient and use low carbon heat from 2025. Although the Building Regulations will only outline performance requirements, i.e. specific technology will not be prescribed, the UK government expects heat pumps and heat networks to be the principal means of producing low-carbon heat for buildings.
Yes. CIBSE has published ‘AM17: Heat pumps for large non-domestic buildings’. This provides consultants and building services designers with an overview of the different heat pump technologies currently available on the market. It also consolidates best practice guidance with the aim of supporting high quality design, installation, commissioning, operation and maintenance of large heat pump systems.
There are two main types of heat pump technology that will be used in low carbon buildings: air source heat pumps and ground source heat pumps. Air source heat pumps (ASHPs) will be the most common units installed, due to their flexibility in siting, reduced disruption to existing systems and their ability to deliver excellent coefficients of performance (COPs). This allows properties to benefit from outputs that are up to 4 times the energy input.
For the majority of non-domestic buildings, ASHPS are capable of providing outputs comparable to gas boilers. For example, the AW Monobloc 90 commercial outdoor air source heat pump is available in 3 models, with heating capacity up to 90kW(EN 14511) and cooling capacity up to 66kW (EN 14511). It can also be cascaded utilising up to 16 units, providing a combined output of 1440kW where required.
As outlined in AM17, certain scenarios may require cascade arrangements of two heat pumps, in order to provide different temperatures, e.g. a higher temperature for DHW and a lower temperature for space heating. In this scenario, one heat pump could provide the lower temperature, with the other further increasing/decreasing the temperatures, without the need for two entirely different systems.
AM17 also provides detailed guidance on how to determine a system’s configuration, as well as size the main products within a system, including the heat pump, buffer vessels and thermal stores. This is the most important process of a heat pump installation and it is crucial for designers to accurately size units for a project. After all, an oversized heat pump can increase capital and operational costs, plus noise and space requirements. Furthermore, efficiencies can be reduced.
It is therefore essential to optimise an entire heat pump system, and there are several additional considerations in AM17 for building services engineers, including:
As part of the latest Building Regulations, new heating systems need to be designed with a maximum flow temperature of 55°C or lower, which ideally suits heat pumps as they typically operate between 45°C and 55°C.As a result, new build properties will have a choice of emitters, including underfloor heating or high performance aluminium radiators. However, in retrofit projects, the most cost effective approach will likely be to use high performance aluminium models.
The benefit of aluminium radiators is the very low water volumes and far higher heat conducting capabilities available compared to steel counterparts. The difference relates to the chemical properties of the two metals, with aluminium's lower thermal inertia reducing the time taken for a radiator to meet the desired temperature. Since aluminium models are quicker to heat up and cool down, there is less chance of 'overshooting' the desired temperature and wasting energy, making them far more suitable for use with the lower flow temperatures associated with heat pumps.
View the Aluminium Range from our sister company MHS Radiators.
Yes, read all about heat networks here.
