Partner: Atkins

As countries gathered in Scotland at Conference Of Parties (COP) 26, the world’s biggest climate change conference, decarbonising the built environment was a major priority for the world’s leading economies. “The World Green Building Council states that together building and construction are responsible for almost 40% of all carbon emissions in the world. An absolutely staggering figure,” says Annabel Clark, Associate Director at Faithful & Gould. Her specific focus is making buildings more sustainable and setting them on their net zero carbon journey. She explains that the energy used to heat cool and light buildings accounts for 28% and the remainder comes from embodied carbon emissions or upfront carbon that’s associated with materials, the construction, the transport processes throughout the whole building lifecycle.

Tackling this is critical if the UK, and the entire world, is to meet its obligations under the Paris Agreement, created in 2015. “The Paris Agreement is a legally binding international treaty on climate change,” says Annabel. “The overall goal is to limit global warming to well below two degrees, but preferably to one and a half degrees Celsius or below compared to pre industrial levels. That is an absolutely mammoth task.”

Global effort

Mammoth because it requires a fundamental restructuring of global energy use as well as commitment from every single country to lower its carbon emissions. To achieve this each of the 196 participants agreed to a nationally determined contribution, which is basically a local target for reducing emissions. “Referring back to COP 26 the hope is that these will be tightened even further in Glasgow. That gives us each, I guess, a carbon budget that we need to work towards on a national basis,” says Annabel. “And that is from the top down. But where we can each make a difference is from the bottom up and it’s all of those smaller pieces that are added together, that will make up our national contribution and feed into that overall benchmark.”

One of the most impactive sectors is the built environment, which itself is fragmented, from the high rise commercial buildings in major cities, to homes in villages in remote parts of the countryside. “So buildings, the construction sector, have a huge part to play in decarbonizing the world and us meeting our climate change challenge and reducing global warming, nationally and globally.”

To do that, Annabel says that building professionals have a responsibility to inspire the people that they work with to go on a net zero carbon journey, but also present the possibilities and the opportunities that they can take and really making net zero carbon easy and visible. “Go as far as possible because doing something is better than doing nothing,” says Annabel

Making changes

Julie Godefroy is the head of sustainability at the Chartered Institution of Building Services Engineers (CIBSE). “The role of buildings is really very important for several reasons, and in different ways,” she says. “Buildings are a very, very large use of heat. And that a very large part of that heat comes from gas.”

Methane gas is a fossil fuel that directly adds to our carbon footprint. “Around 85% of homes rely on gas, which means that either we need to find another way to heat them, or gas needs to decarbonise.”

There are alternatives but this won’t be an easy transition. “The hope is, and the scenarios are, that a very large portion of buildings and homes will move to heat pumps,” says Julie explaining that this would be coupled with heat networks, small, very energy efficient buildings and a little bit of directly electric heating.

Just this month the UK government announced its Heat and Buildings Strategy where it launched a £450M boiler upgrade scheme that would make grants of £5,000 available to homeowners who want to switch from gas boilers to heat pumps. This would be part of what it described as a gradual shift away from gas. It also committed to making major decisions on the use of hydrogen for heat instead of natural gas by 2026.

Demand management

Reducing demand for both electricity and heat is another measure that could reduce emissions. “Clearly, a lot of non-domestic buildings are not operating as efficiently as they could for all sorts of reasons,” says Julie.

Improving this is critical because according to the World Green Building Council, 80 percent of the buildings that will exist in 2050 are already here. So retrofitting buildings to lower emissions is critical and this means tackling operational carbon. “So we want to look at that through energy efficiency, decarbonising heat, and then decarbonising power, and then dealing with any residual emissions as a last attempt, so through carbon offsets, but absolutely, we want to focus on reducing the energy demand of a building first,” says Annabel.

But you can’t reduce demand until you understand the carbon emission profile of a building and this is where a lot of building owners need help. Some major property owners don’t even know what buildings they own let alone what their carbon footprint is. “First and foremost how do you make carbon visible?” asks Stuart McLaren, Net Zero Director for Infrastructure at Atkins. He says that often building owners don’t have the data that they need, or they don’t know that they have it. “They may have it, they may not even know they have it, they don’t even know where the data is coming from, or how to store it, how to manage it. And so for me, first off, let’s make carbon visible so that people can create deliberate insights to enable informed decision making.”

Understanding investment

The next stage is to understand which carbon reduction investments will make the biggest difference, and then accessing the right information at the right time to inform the business case. “Because if you can’t fund this, it doesn’t happen,” says Stuart.

Once the investment is made, the new systems have to be integrated into the building systems so that this visible carbon is then managed effectively. “This is going to be how do we take this view of carbon and just integrate it and make it part of their business as usual, that it is just an element of a more holistic approach to managing their assets,” says Stuart.

Once this is done Stuart wants organisations to share their innovative ways of decarbonising their assets so that others can learn from it. All of this adds up to a concept that Stuart describes as decarbonomics, which in practice starts with an exercise in benchmarking to capture the data needed to understand the carbon emissions of the building. The next step is analysing this data. “Turning that data into those really distinct insights, that can be presented in an incredibly intuitive way, mindful that you’ve got multiple users of these things, there’s not just one group or one person that interacts with this information,” says Stuart.

Only when you have all of this data can you then move into the delivery phase where measures can be implemented to make the building more carbon efficient “For instance, like the work we’re doing with the Government Property Agency now as their strategic partner, where we are supporting them as their delivery partner in the interventions for their, for their portfolio,” says Stuart.

The Government Property Agency is reducing the carbon emissions for 420 buildings over the next four years, removing about 1,300 gigawatts of energy out of their estate. “So we’ve started looking at 24 buildings in the first year and into growing to sort of 56 buildings across the UK in the second year, and then that ramps up into the final three years of the programme,” says Peter Dunn, Associate Director at Faithful and Gould.

Projects range from simple to complex and the interventions broadly fall into four categories. The first is replacing the lights. Light emitting diode (LED) lights are 90% more efficient than traditional incandescent bulbs making this an easy win for building owners. Combining this with PIR controls means that these are only activated when there are people in the room saving even more energy. The next major area of focus is in decarbonising the heating systems. “Removing gas boilers and looking to instal air, air source heat pumps and electric heat pumps and facilitating moving to more green energy supplies,” says Peter.

And then there are the heating ventilation and air conditioning systems to consider, followed by green energy generation and storage. “They’re also looking at photovoltaic technologies, energy storage, as well. Then the other one that is being reviewed is the building fabric and what benefits can be done to the existing buildings,” says Peter.

Of all of these Peter says that it is the heating systems where he can see the biggest carbon savings. “The biggest impact typically is around the air source heat pumps and that technology that we’re seeing more and more coming into buildings,” he says.

Air source heat pumps absorb heat from the air outside using a fluid that is then run through a compressor which then transfers this heat to the hot water circuits in the building. Peter says that what they are learning from the GPA work is that there are a lot of simple measures that building owners can take to save carbon straight away.

Residential challenge

Getting going in the commercial sector might make sense for owners of multiple properties where saving carbon isn’t just the right thing to do, it is also saving money in the long run.

What is a much bigger challenge is decarbonisation of the residential sector. Commercial, industrial and educational providers have the capacity to raise finance to implement emissions saving measures, but most homeowners don’t.

To get an idea as to the extent of the challenge Atkins has been investigating the scale and cost of the energy efficiency measures that are likely to be required across the country if we are to tackle decarbonising heat and power in homes. “So in the UK, about 75%, of all building stock is residential. That’s calculated by floor area,” says Ruth Hynes, Senior Design Researcher at Atkins

Ruth and her team have been using energy performance certificate (EPC) data for homes across England to analyse their energy efficiency. These EPCs are required by law for any buildings that are built, sold, or rented. And so came in in about 2012. Not buildings have an EPC, but about 60% do. “So we’ve been using that data to create heat maps of basically the building topologies, the energy efficiency of them and then kind of trying to understand what the scale of the retrofit challenge would be in different areas,” says Ruth.

EPC certificates give homes an alphabetic rating from A, being the most efficient so a fully insulated home producing its own power through photovoltaics for example, to G being a home using expensive fuel such as oil or liquid propane gas, with little or no insulation. There is an ambition by the UK Government to upgrade existing houses to EPC band B or C by 2035. Currently, approximately 68% of buildings in England and Wales are D or below.

So 68% of residential buildings would need to be retrofitted. “There’s an argument that that’s not ambitious enough that EPC bands of B and C won’t actually get us to net zero by 2050 and what we should be aiming for is an EPC band of A, and that is highly ambitious,” says Ruth. “But if we were to take that, we’re looking at approximately 97% of the building stock to be retrofitted. So it shows the scale.”

What is interesting about the findings is that there are trends emerging about the kinds of measures that would be needed to improve energy efficiency and hence the carbon emissions profiles of buildings around the country. Comparing Manchester to Glasgow, for example gives interesting results: “Approximately 75% of homes in Manchester are either detached or terrace. So the types of interventions that they would be looking at would be different from Glasgow, because Glasgow has about 73% flats. So the topology is completely different, the interventions that you would have would be different, the cost associated to those are different as well,” says Ruth. It also means there are different types of ownership.

Knowing the building types and the measures already in place means that for any location this dashboard can be used to suggest appropriate carbon saving measures. Ruth says this is aimed at being used by local authorities. “So the most of authorities will have a net zero strategy that will include building the building sector in some way. And so by looking at this, they can see whether, you know, for example, there’s a large proportion of flats in the area, and potentially they might own and manage a large portion of those flats as well. And then what this aims to do is help to understand what the potential for those different interventions is, so is the most benefit going to come from insulating all external walls and roofs? Is there a greater benefit for photovoltaics? And what the potential cost might be for that? But then also what are the long term benefits, and what the payback period would be for that initial investment.”

The data is broken down into very detailed analysis with a figure of average carbon saved by pound spent. Taking all of this into account means that hard data is emerging as to what it will actually cost to retrofit the UK’s residential stock. For example looking at information for Scotland tells us: “To retrofit to EPC rating of A in Scotland, we found the average cost would be between 18,000 and 35,000 pounds, which is higher than some other estimates. But is related to the fact that we include quite a few different interventions and what we’re looking at so not just insulating a property, but changing the heating system and adding photovoltaics.”

This then translates to a carbon saving of somewhere between 120,000 and 380,000 kilos of carbon per property per year.

With all this new data, the scale of the challenge for both residential and non-residential buildings is becoming increasingly clear and it throws up new questions about how this can be funded. How can property owners can be incentivised to make these changes? The public sector is beginning to implement emissions saving work like that of the GPA with its 400 buildings programme and planning rules can be used to insist on energy efficiency in new construction. But for the private sector and individual homeowners there are less incentives to make changes to existing buildings.

But pressure is increasing on the UK to begin the most difficult work required to get us to net zero by 2050 and fulfil our commitments under the Paris Agreement.