Passiv UK Q&A

William Heinzelmann, Product Director at Passiv UK, speaks exclusively to InstallerSHOW about the heat pump sector and how efficiency can be maximised.

Is enough being done at a government level to facilitate mass market decarbonisation of heat?
Currently, heat pump installations are well below the Government’s target of 600,000 a year by 2028. Just 55,000 were sold in 2022 and the National Audit Office has warned the target is unlikely to be met (more info here).
Despite this, the Government has implemented several policies to support uptake. For example, the Boiler Upgrade Scheme offers a generous £7,500 towards heat pump installations and the requirement for loft or cavity wall insulation has recently been dropped, making the scheme easier to access.
In April 2025, the Clean Heat Market Mechanism will also come into force which will create a market across boiler and heat pump manufacturers that should encourage them to discount the cost of their heat pumps.
Looking ahead, the Future Homes Standard is currently being consulted on and will prohibit the installation of gas boilers in new build homes starting from 2026. Heat pumps are expected to become the primary alternative for heating in these new homes.
However, a significant challenge is the recent Government U-turns and policy changes on green initiatives, that do not create a stable environment for businesses or individuals to invest in low-carbon technology. This kind of uncertainty is not helpful to ‘facilitate mass market decarbonisation of heat’.
Government focus to date has also been very much on heat pumps, rather than heat pump controls. Controls can make a huge difference to the affordability of a heat pump and are critical to their effective installation and operation.
Heat pumps need to operate at low flow temperatures to deliver high efficiencies and low heating bills. Current heat pump controls manage this flow temperature in a very crude way. Smart controls like those from Passiv can dynamically optimise heat pump flow temperature according to the learnt thermal performance of a building and local weather forecasts. The Energy Savings Trust has verified that the Passiv controls increase the Coefficient of Performance (CoP) of a heat pump by 17%.
The Passiv controls are also designed to optimise energy usage according to ‘time of use’ energy tariffs and rooftop solar panels, potentially reducing a homeowner’s heating bill by 30%. While smart controls aren’t critical for boilers, they significantly impact heat pump efficiency. We urge the Government to prioritise controls, as they could greatly enhance heat pump adoption. According to the National Grid, just a 10% increase in heat pump efficiency could boost uptake by 15% by 2028, underscoring the vital role of smart controls like Passiv’s.

Do you believe punitive measures such as the Clean Heat Market Mechanism could result in a backlash against technologies such as heat pumps?
We need to change the narrative that heat pumps are a new, unproven technology that for whatever reason, won’t work in UK homes. Heat pumps can deliver better, more consistent comfort in your home, massively reduce your carbon footprint, and when paired with the right smart controls, can dramatically reduce your heating bills.
There is a lot of negative publicity in the media about heat pumps and a campaign to increase public awareness of the technology, as recommended by the National Audit Office, would be welcome.
There are a lot of myths to be dispelled, for instance; does the average homeowner realise that a heat pump uses the same technology as a fridge (but in reverse)? Do they realise a heat pump is an air conditioner that does heating? Or that in Sweden, Norway, and Finland (the three coldest countries in Europe), over 40% of the population has a heat pump?

Does the transition from gas boilers to heat pumps necessitate a shift in mindset when it comes to controls?
Absolutely. Most boilers are controlled using a crude thermostat that simply switches a boiler on or off. There is little incentive to do better with boilers – smart controls will deliver little improvement in efficiency and the high operating temperature of a boiler means ‘comfort’ is simple with radiant heat being provided from radiators very quickly.
However, operating a heat pump in a similar way is a disaster. Crude on/off controls will cause the heat pump to run inefficiently, cycling on and off at an excessive flow temperature. They also don’t deliver good comfort – heat pumps take longer to warm up a home and appropriate preheating is essential.
Smart controls, like those from Passiv, that can dynamically optimise heat pump flow temperature, are essential for a good heat pump installation. The Passiv controls operate a heat pump at the lowest possible flow temperature while maintaining homeowner comfort through smart preheating – with both being adjusted to the specific characteristics and local weather conditions for the building in which they are installed.
Smart controls, when considered alongside the cost of installing a heat pump, are an extremely inexpensive way of improving the outcomes of a heat pump installation.

Incorrect installation and commissioning of a heat pump system is often cited as the reason for higher energy bills. What can be done to overcome this issue?
High energy bills may indicate that a heat pump is not operating efficiently, often due to improper commissioning, resulting in incorrect flow temperature settings.
One-third of heat pumps are installed and commissioned to operate at a fixed flow temperature, which may be convenient for installers but is very detrimental to the pump’s efficiency. The remainder use a weather compensation curve, where the heat pump operates according to the outdoor temperature. This is better for the efficiency of a heat pump, but it’s a very difficult thing to set correctly. It doesn’t change if you get it wrong or adjust to new information, and it can’t look at weather forecasts or factor in how the homeowner uses their heating system.
The Passiv controls have been designed to work with a heat pump. They remove the need for an installer to set a weather compensation curve. Instead, they learn how a home heats up and cools down and how the heating system behaves. They then use local weather forecasts to calculate the optimal way to meet a homeowner’s comfort requirements, continuously optimising the heat pump’s flow temperature to maximise its CoP. Energy Saving Trust verified that the Passiv controls increase the CoP of a heat pump by 17% against a manufacturer’s standard weather-compensated controls.

How can Greener Grid Payments further encourage end users to embrace heat pumps?
With more people buying heat pumps and electric vehicles, demand on the electricity grid is forecast to increase dramatically over the next few decades. At the same time, our electricity is increasingly being provided by intermittent renewable sources of generation, like wind and solar power.
Demand Side Response, which involves homes and businesses adjusting their power consumption at specific times, is becoming increasingly important to help balance the National Grid. Passiv Greener Grid Payments is the UK’s first domestic Demand Side Response service for heat pump owners. Greener Grid Payments pays Passiv customers for using their heat pump – as part of the service, we automatically adjust a customer’s heat pump consumption during grid events while maintaining their comfort through smart preheating.
Customers do not need to take any action, the service is completely automated and will not impact their home comfort. The service runs over winter and this year, top-earning customers received over £65 for taking part. This payment is in addition to the 30% heating bill reduction from the Passiv controls. When combined, these benefits contribute to making a heat pump an affordable alternative to a gas boiler.

For more information, visit www.passivuk.com or head to stand 5G92 at InstallerSHOW.
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