Zero carbon homes

…but why we must push for an accelerated Zero Carbon Energy Policy.

It’s déjà vu all over again. A Zero Carbon Buildings Policy is well-intentioned but misguided. We must push for an accelerated Zero Carbon Energy Strategy.

We can’t afford to make the same mistakes we made last time around. We mustn’t push to introduce a Zero Carbon Buildings or a Zero Carbon Homes Policy – either nationally or locally. We need one policy for energy efficient buildings and a separate policy for zero carbon energy.

This is a point of pain for me. The last Zero Carbon Homes Policy was misconceived and unworkable. I saw it develop and was horrified. It was not rooted either in reality or good sense. I was not sorry to see it axed by the government in 2015 – though I was sorry to see the UK’s commitment to a zero carbon future undermined.

A building or a real estate development is not the right scale at which to push for zero carbon. Sometimes it can be right – for example in a low-density development where the roofs can be covered in PV, but often it simply is not – for example in a high-density urban setting. If a developer wants to construct a zero carbon building or net zero carbon building, then fine. This is why I am supportive of guidance to developers on how they might do this – for example in guidance produced by the London Energy Transformation Initiative (kudos to Clara Bagenal George for driving this and rallying support). But this is completely different from introducing a policy to force a developer to do so. 

Let me give you some more reasons.

First, the idea of including so-called ‘plug loads’ as part of a building’s emissions is unhelpful at best, silly at worst. The emissions from energy consumed by a building can be divided into ‘regulated emissions’ from heating, lighting, cooling and the like, and from appliances or ‘plug loads’ arising from computers, televisions, cookers, etc. Why should the building (or the developer of the building) be responsible for all carbon emissions from appliances and activities which residents, tenants or workers in the building might release, even if we knew what these would be? 

Take my laptop. When I plug this into a socket in a building, why should the housebuilder or developer have had to deal with the emissions from charging it? Why not the laptop manufacturer? I take my laptop from a new net zero carbon building to an old building and it goes from clean to dirty. If I plug an electric car into my building, is it now counted as part of my building emissions? It doesn’t really make sense. Should we have a Zero Carbon Laptops Policy, Zero Carbon Televisions Policy, Zero Carbon Cookers Policy and a Zero Carbon Electric Cars Policy? Probably not, but we should have a Zero Carbon Energy Policy so that all our energy use, whether in a new building or an old one, inside or outside a building, is heading to zero carbon. 

Let’s get leading players across all industries rallying behind an accelerated national Zero Carbon Energy Policy so that each part of the system can then take its fair share of the costs and reap its fair benefits as we transform to a zero carbon future.

Second, building on the point above (excuse the pun), a Zero Carbon Buildings Policy is an unfair tax on new buildings and new homes. Many, if not most, of us don’t like developers, often with good reason. But to slap a blanket carbon tax on them and ask them to pay for our emissions is not right. Indeed, developers will say it is an unfair tax and play it off against affordable homes – which is exactly what they did last time – creating a dangerous and unhelpful narrative: ‘Do you care more about affordable homes or the environment?’.

Third, the concept of ‘allowable solutions for net zero carbon’ which often accompanies discussions of a Zero Carbon Buildings Policy is unsound. It is the idea that the developer offsets emissions, either by: investing in reducing emissions in the surrounding area (e.g. by insulating homes); committing to buy green energy to cover all the buildings emissions for a set time; or, investing in additional renewables offsite to create a ‘net zero balance’. 

There are too many problems to go into detail here. But it assumes energy modelling is correct; and we know energy modelling is problematic as soon as we take human behaviour into account. With rapidly changing consumer appliances – what appliances and devices will we be using in five years, let alone fifteen years – will they consume more energy or less energy than today? Then there is the problem of defining when is a renewable energy source additional. Additionality is not trivial to define. Take a wind farm, is it additional: when it is simply an idea; when it has planning permission, but before it is fully financed; or, when it is fully financed and under construction, but not yet operational?

Fourth, when developers are forced to install on-site renewables, the outcomes are often not good. Developers are not energy generation or supply companies – nor should they be. When we require developers to install decentralised renewable and low carbon energy systems we often push technology into places it is just not happy to go. Last time around we saw solar, CHP and district heating systems installed to meet planning conditions, but sometimes not even switched on. Let’s not even go into the operational and maintenance challenges.

Fifth, decentralised energy will have its place, but big renewables are still the most important way to get carbon savings cost-effectively. Losses in transmission exist, but they are relatively small (around 8%) compared to the sheer efficiencies and economies of scale with large renewables. (For example, a wind turbine with twice the diameter in a location twice as windy will generate 1,600% more energy).

Big renewables currently account for the vast majority of UK renewable generation. Decentralised renewables remain a small (but useful) part of the mix. For example, small solar PV installations (less than 4 kW) account for 2% of renewable generation or less than 0.7% of all electricity generation in the UK[i]. As we enter a major economic crisis, we must recognise that the big, cost-effective carbon savings are coming from big renewables such as offshore wind. We must support decentralised energy and community-owned energy. For example, though incentives such as grants. But we must not push technology or developers too far beyond their comfort zone. This will simply waste money and make new buildings and homes less affordable in the process. The same will go for battery storage. Don’t force decentralised battery storage. Incentivise developers to put them in, but recognise that the bigger future in the near and medium term is in battery storage at city and region scale. This is being done in many places around the world.

So, what should we do? I want developers to focus on building beautiful homes and other buildings. These buildings must be designed to be good for people and support thriving communities where, for example, people can reduce their dependence on cars. Developers must be required to focus on a fabric first approach with a requirement to do the simple things like build to very high U-values for walls and windows; to make building efficient and be required to build them with a high level of air-tightness. I want to encourage and require them to reduce the embodied carbon of materials. I want old buildings to be retrofitted to make them more efficient and to generate jobs. 

Completely separately, I want a decent national (and if needed city and region) zero carbon energy strategy; promoting rapid deployment of large scale and decentralised renewables in a way that the renewable energy industry can delivery coherently. This will enable the energy industry to collaborate with willing developers in a way that works for both. 

For me, all buildings must be energy efficient and run on renewables whether they are generated on-site or off-site. We must aim for a future where all buildings are zero carbon, but this is different from a Zero Carbon Buildings Policy. All our vehicles and appliances must be zero carbon too.

So, let’s not introduce a Zero Carbon Buildings Policy. Let us not tax new buildings and new homes or try to turn developers into energy companies. It didn’t work last time and it won’t work this time. Instead, let’s promote decent, energy efficient buildings and join with other industries and lobby for a coherent Zero Carbon Energy Policy. 

We simply cannot afford to repeat the mistakes made last time round. We neither have the time nor the money. Simple is better and less is more.

[i] Small scale PV accounts for 20% of solar generation, which in 2018 was 11.7% of renewable electricity generation, which was turn 33% of UK electricity generation, giving the net figure of 0.7% of all electricity.



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