5 ways to a successful heat pump deployment – #1 Optimal Sizing

Blog series - Climate change plays a central role when making plans for a better future. And the decarbonisation of the public sector is top of the list.
Chris Davis

Chris Davis

An article by Chris Davis

Climate change plays a central role when making plans for a better future. And the decarbonisation of the public sector is top of the list. To help England along, the government is giving it another push in the back with a third round of the Public Sector Decarbonisation Scheme.

Reducing carbon emissions, is a climate mission

Decarbonising heat is one of the biggest challenges to achieve net-zero by 2050. Nowadays, natural gas is still the predominant fuel for heating buildings and water, but alternatives are already available. One of the most popular ones? Heat pumps. Although they are not like-for-like replacements for gas boilers, if applied correctly, they have the potential to deliver immediate carbon emission savings. For ultimate impact however, good practice system design is essential.

The secret ingredients to our optimal recipe

The design and optimisation of heating and cooling installations is becoming increasingly complex, and all too often we see the investment in low carbon solutions fail due to insufficiently well-thought-out design by M&E consultants.  A whole system approach to the design and deployment of heat pumps within a building is crucial for optimal impact. So, in the spirit of being transparent on how design matters for your system’s performance, we will be sharing the 5 areas that need ultimate care, for a successful deployment of your low carbon heat pump installation. First one on the list: Optimal Heat Pump Sizing!

Size really does matter

First things first, what is optimal sizing? Optimal sizing will be a balance between upfront capital investment costs, carbon emission savings and your annual energy costs. Consultants or installers often base estimates for sizing of plant on assumptions about how the whole installation might perform in peak load conditions. Peak loads on the system may only occur for 1% of the year, with the installation running at much lower “part load” thermal capacity for the majority of the time.  It therefore makes sense to utilise existing or lower capital cost boilers to deal with these peaks and size heat pumps for an optimal balance between upfront capital investment costs and carbon emissions.

With the carbon intensity of grid electricity having decreased rapidly over the last few years, heat pump systems now have the potential to deliver immediate carbon emission savings. However, the so-called “spark gap” which exists between the cost of natural gas and electricity means that there will also be a trade-off between the fuels in terms of annual energy cost.  Optimal sizing therefore will be a balance between upfront capital investment cost, reduction of carbon emissions saving, and annual energy costs. 

The traditional method for calculation always falls short when designing an HVAC installation, simply because too many parameters need to be considered simultaneously. The importance and impact of correct hydraulic SYSTEM design is something that is still not well enough understood by mechanical engineers and installers – the very “experts” building owners are relying on.

Calculations are usually done in Excel; based on a single, “worst case”, full load operating condition; and include a margin for error that is big enough to avoid any uncertainty and risk, resulting in installations that are over-dimensioned, meaning the true contribution to the system from the new heat pump and how it will really perform, are difficult to judge. 

That’s why having transparency over the behaviour of the installation in its entirety and control strategy, are vital for being able to make the right choices. Including the effects of continually varying system temperatures and weather conditions on boiler and heat pump efficiency, is a must.

The key ingredient for optimal sizing then is the ability to quickly and objectively compare the impacts on capital costs, operational costs and carbon emissions of different heat pump and thermal storage capacity options, as well as different hydraulic integration and control strategies. And that’s exactly what our digital modelling tools do. Accurately simulate and quantify scenarios, so you are guaranteed to be able to make fact-based decisions, out of multiple options, to find the best fit for your buildings.

Now, let’s get moving!

Successful implementation of low carbon heat solutions, require coordination and expertise. To address these challenges, Hysopt has developed tools and personal dedication to analyse challenges and implementing solutions that benefit both your organisation and our environment.

Take advantage of Hysopt’s unparalleled expertise in optimising heating systems by using our FREE low carbon heat optimisation calculation to support your application bid. Our calculation will help you understand the potential carbon, energy cost and capital cost impacts a properly optimised low carbon heat solution can make; and provide you with all the key metrics required for your full PSDS application.

PS: stay tuned for our other 4 “must know areas” to guarantee an optimal low carbon heat pump deployment!  Or if you can’t wait, you can download our e-book right away!

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Validated by ISSO
The Hysopt software has been validated by ISSO. The report literally praises our software as a 'powerful tool for optimizing HVAC systems'.

Roel Vandenbulcke



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Chris Davis

Chris Davis

Ontwerp zonder titel


Creating digital life
A Digital Twin: Creating a virtual space with a virtual model of your systems, so you can make an informed decision before making a real life one.

Roel Vandenbulcke