In the second edition of House build Magazine, we covered heat pumps, electric boilers, infrared heating, hydrogen, thermal batteries, underfloor heating, microwave boilers, mechanical ventilation with heat recovery and district heating. Since then, things have moved on a little with a couple of new technologies offering yet further options to heat our homes.

Heat pump ventilation (HPV)

HPVs are a whole house, single unit ventilation, heating, cooling and hot water system which replace the traditional boiler, hot water cylinder and ventilation units.

They use a thermal store to heat at night, taking advantage of off-peak electricity rates, while taking the heat from stale exhaust air to condition fresh air. During the summer, incoming air is cooled to keep home temperatures down.

Ventive is one company offering such a product and claim a 20 to 100l/s ventilation rate, producing up to 300 litres of hot water at 45 degrees Celsius and heating air up to 6kw at 40 degrees Celsius. The price is not yet clear but expect to pay over £5,000 per unit and for retrofitting, the need to fit air ducts will make costs spiral.

Heat battery boiler

Much like the Ventive, heat battery boilers use a phase change material to heat hot water and are being sold as a product where you charge at night at off-peak rates. One company who is pushing their way into this market are Tepeo, with their Zero Emission Boiler, or ZEB.

Using a smart charging algorithm, the system charges itself up at the cheapest or greenest time of the day and is currently being tested to take advantage of any renewable energy generation, for example: solar, that a property may have.

The limitation of ZEB is it requires a wet heating system and hot water tank and it’s price is proving a slightly tricky sell at more than £6,000. However, they are easy to install and ensure that the higher temperature radiator expectations that most homes have can be retained.

Propane refrigerant heat pump

Research in Germany which explored monoblock heat pumps using propane as the refrigerant have borne fruit, with Mitsubishi and others announcing a monoblock with heating capacity of 5kw, 6kw and 8kw. 14kw is also slated for the future.

The benefits of this heat pump are that it can produce hot water up to 75 C with external air down to -15 C, or up to 65 C for air temperatures of up to -25 C. A hydro module as an internal unit or a buffer tank for hot water storage can be added. This means that any home can have a heat pump, without major changes to the heating system, such as radiator changes.

This is a tweak on a technology, but tweaks are important, particularly in the UK, where electricity prices are not dropping at anywhere near the levels that renewables energy solutions, such as solar panels, are.

Hydrogen fuel cell boiler

Costing between £12,000 and £17,000, the hydrogen fuel cell is a different beast entirely as it can generate electricity while also heating your home, which means you can get a return by selling excess energy to the grid.

Vitivalor uses natural gas to charge its fuel cell by removing the hydrogen and cleaning up the gas, while using an exothermic reaction to heat a water tank. It can produce a maximum of 18kW of electric energy in a single day.

The PT2 model by Veissmann, which is a monster of a unit akin to an art installation, offers an integrated direct hot water cylinder of 220 litres and total thermal output of up to 30.8kW.

Hydrogen fuel cells are new to the UK but not Japan, where they have been around for some time; however, with so much heating system competition and the use of natural gas being phased out, the UK government has been slow to commit to any technology but heat pumps and only the air to water variety. This is beneficial for direction but concerning as quality heat pumps engineers and designers are already thin on the ground, and those who have been installing them for many years are now complaining that they are losing their supply chain.

Electricity needs to be cheaper!

Unfortunately, until SAP and EPC’s accept different technologies as part of their assessments, or the UK reduces the cost of electricity by half, which is what some European nations pay, the path to net zero is going to remain spiky for many people and confusing for housebuilders who are expected to build net zero housing under next to zero energy strategies.

Rico Wojtulewicz

Head of Housing and Planning Policy

National Federation of Builders