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Detailed Design and Heat Loss

Detailed Design and Heat Loss Calculations

In order to produce a detailed design and specification for your system we will need to do comprehensive heat loss calculations. These are produced following the very robust Microgeneration Certification Scheme (MCS) methodology which is intended by the government to protect customers.

These design calculations take into account the size and construction of each room. We have to consider the amount of insulation in the walls, floors and ceilings as well as doors and windows. Additionally there is a room design temperature and ventilation rate which depends on the room. These room by room calculations are then combined to produce the total heat loss for the entire property. This is used to accurately determine the size of the heat pump and the specification of the heat emitter system i.e. radiators or underfloor heating pipework.

Getting these calculations right is essential for specifying the correct heat pump but also ensuring effective heating for a comfortable warm building.

These calculations can be very time consuming to produce so whilst an initial design is free of charge, a detailed quotation will be incur a cost of £300, which will then be discounted from the contract price i.e. there is no charge if a project proceeds.

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What assurances do I have that the design will be correct and accurate?


One of the main benefits of the Microgeneration Certification Scheme (MCS) is ensuring that there is a very rigorous process in place for the system design. All MCS accredited companies are audited on an annual basis to ensure that these standards are being maintained; it is essential that your heat loss calculations are performed by an MCS accredited company.


There is no law to mandate MCS accreditation for a heat pump installation and before the Renewable Heat Incentive (RHI) scheme was launched many heat pump systems were designed and installed where only crude heat loss calculations had been performed in order to save time and money. However, many of these systems cost considerably more to run than the customer was initially led to believe, the short term savings from installing an underside system are massively outweighed by the increased running costs. We are proud to say that all of our heat pump installations have been in accordance with the MCS design criteria.

What if I already have an EPC?

You may already have an Energy Performance Certificate (EPC)  for your property which may show a heat loss calculation. Although this assessment will have been done to regulated standards it is not sufficiently detailed to be able to base a detailed system design on; it takes far less time to generate an EPC than it does to perform a complete MCS heat loss calculation, as such it is possible that the EPC will underestimate the actual heat requirements of your building. The MCS rules require that we follow the MCS standards for the heat loss calculation and system design for any system that will be MCS compliant. If your design is not MCS compliant then your system will not qualify for Renewable Heat Incentive (RHI) payments.

How Much Does A Detailed Design Cost?

We provide the MCS heat loss calculations, detailed design and quotation free of charge for customers that proceed with the installation. If you choose not to proceed with the installation from Orangehouse Renewables then we will retrospectively charge £400+VAT for this design work to compensate for the considerable time and effort spent in preparing it.

Our Price Promise

If the quotation we provide following our detailed design turns out to be more than 15% higher than our initial free quotation then we will not apply any charges for this service even if you choose not to proceed with the installation.

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