Hackney, Heat Pumps, and Bionic Duckweed

Hackney Council is delaying new homes because they can’t connect to a district heating network, but there’s a small problem.

‘Bionic duckweed’ is a term coined by the economist Stian Westlake to describe a specific failure mode of policymakers. It happens when they make the perfect the enemy of the good, or as Westlake puts it ‘the future the enemy of the present’. The term is a reference to a 2007 Transport Select Committee hearing where the journalist Roger Ford attacked the Department for Transport for deciding against funding rail electrification because “in 15 years time … trains might be powered by hydrogen developed from bionic duckweed… and we might have to take the wires down.” On the narrow point of rail electrification, history has been kind to Ford. I believe Hackney Council is making a similar mistake. Let me explain.

This is 10-24 Lamb Lane in Hackney. Standing on it currently is a derelict office block built in the 1950s. For the last five years, Hackney businessman Ben Chesterfield (pictured) has been battling with the council to obtain permission to re-develop it and turn it into this.

When complete, it will include 19 newly-built flats and 10,000 square feet of new office space. Chesterfield wants to do the right thing both environmentally and for residents’ bills, so the flats are designed to be extremely energy efficient and heated via low-carbon heat pumps.

The original plan was for all of the homes to be heated via a single communal air-source heat pump, however after talking with experts Chesterfield identified a better solution. They told him to swap out the communal air-source heat pumps for new exhaust-source heat pumps, which capture warm indoor air from kitchens, bathrooms, and utility rooms.

Exhaust-source heat pumps don’t work for every property but for extremely well-insulated properties like the ones Chesterfield wants to build they are a good option. There’s an added benefit for residents for switching. Communal systems mean complicated communal billing and maintenance arrangements. Individual heat pumps don’t.

This is a real concern. For example, one development in Greenwich saw residents hit with a surprise £200,000 heating bill due to issues with the billing arrangements.

The expert analysis suggested that using an exhaust-source system would be more than twice as efficient as a communal system. In terms of emissions, installing the latest exhaust-source heating technology across the 19 flats would produce around 3.5 tonnes of CO₂ per year — almost 27% lower than the 4.8 tonnes produced by a district heating network supplied by air-source heat pumps. Compared to communal heat pumps producing 7.4 tonnes per year, the exhaust-source system would mean 3.9 fewer tonnes of CO₂ were emitted each year, a cut of more than 50%. And that’s comparing heat pumps, relative to gas we are looking at 23 tonne annual saving across the 19 flats

Hackney Council declared a climate emergency in 2019 and have pledged to reach Net Zero by 2040. You might think then that the developer’s request to switch to an even greener option would be swiftly approved. You would be wrong.

Under Sadiq Khan’s London Plan, the whole of the capital is designated a Heat Network Priority Area, creating a presumption that developments should use communal systems with the ability to connect to a district heating network.

Unlike the communal heat pump, individual exhaust-source heat pumps cannot be connected to a district heating network. As a result, Hackney Council is blocking the change.

There’s just one small problem.

There is no district heating network for the development to connect to. Nor are there any concrete plans to build one it could connect to. The council has highlighted areas where heat networks could be viable (with additional grant funding), but none that cover this building. There is a proposed heat network nearby that could, in theory, be extended to cover the property, but as it stands, there is no business case, no planning application, and no funding secured.

In fact, there is just one district heat network in Hackney – the Shoreditch Heat Network – which serves three estates in the area. It’s cut emissions, but it has not been without problems. The BBC recently reported that hundreds of residents have been left without hot water this winter due to frequent outages. The article quotes one resident who ‘resorted to boiling saucepans of water in order to have a hot bath’ because her taps didn’t run hot enough. She also claimed one Hackney official told her to leave her oven door open for a few hours. (Hackney denies this latter claim.)

This isn’t to say heat networks can’t work. Visit Copenhagen and you’ll soon be disabused of that notion. In the Danish capital, 98% of buildings are heated via district heating. More of Britain’s homes, particularly in cities, could and probably should be heated via them.

Still, the developer’s exhaust-source heat pump is cheaper and greener than a communal heat pump connected to a district heating network. The experts who advised him to switch to exhaust-source heat pumps estimated that a communal heat-pump attached to a district heat network would use more than a third more energy (about 1.2 tonnes more CO2 each year).

In other words, Hackney Council isn’t making the perfect the enemy of the good. They are, incredibly, making the good the enemy of the perfect.

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As the process dragged on, Hackney eventually (or at least appears to have) conceded the point that incompatibility with a non-existent (and unplanned) district heating network wasn’t sufficient grounds for blocking the more efficient heat-pump. However, they haven’t given the developer the green light yet. The Council are now demanding more evidence on the merits of the proposed heating system. It’s a slow process. As developer Ben Chesterfield notes, there’s a lengthy back and forth with month-long gaps between council responses.

All of this adds cost. With the building’s existing tenants out and work ready to begin, Chesterfield reckons that each month of delay costs something like £20,000. Add to that all the specialist reports he needs to commission, which he tells me cost ‘probably another £10,000 per month’. Trying to do the right thing for residents and the planet isn’t cheap.

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It is often assumed planning regulations protect the environment. Yet our biggest environmental problem is climate change and it isn’t being caused by new development, it is caused by us continuing to burn fossil fuels to do things like heat our homes.

Just as it was an error to stall electrification because trains might one day be fuelled by green hydrogen (or bionic duckweed), it is a mistake to block a housebuilder from installing ultra-green exhaust-source heat pump because they can’t one day connect up to a district heating network that might never be built.