The Big Rebuild: One-Week Zero-Carbon Home Makeovers and Setting New Comfort Levels

‘Build, build, build’ is a call heard to boost economies trying to bounce back from the economic impact of the coronavirus crisis. But, facing the climate emergency there are huge opportunities to ‘retrofit, retrofit, retrofit’, improving buildings that are already standing, as well as rethinking some of the assumptions that make buildings so energy-hungry in the first place. Is it time to question the so-called Fanger equation that’s been controlling our energy use for half a century, and embrace Energiesprong and Stroomversnellung?  The built environment looks set for a long-overdue makeover.

It’s fifty years now since the Danish scientist Povl Ole Fanger published his research in 1970 about how warm people like to feel, the so-called thermal levels of comfort for the human body. His – all male – participants were exposed without clothing to a range of temperatures and then asked about their levels of comfort which were measured on a seven point scale. Their physiological reactions were also measured. The equation resulting from this work still exerts an invisible influence that governs the designed-in temperature of our modern buildings, and hence our use of energy. This is because it became embedded in global construction standards. As a result, despite all of us having different metabolisms and body shapes and sizes, we are usually required to work seated in a space that is heated or cooled to 21-22℃. When clothing is added into the calculations of engineers and architects, it is also measured in “clo” – or a man’s business suit of: trousers, a long-sleeved shirt and a jacket. All at once, therefore, buildings designed this way fail to consider many more than half of humanity: women, people from cultures where suits are not worn, or those whose metabolism is just different because of age, size or health. The incorporation of Fanger’s equations into building codes to create a set-point for comfort not only locks in assumptions that only apply to a male, suited minority, but also a level of energy use and hence carbon emissions which, in aggregate, contribute to the climate emergency. Their very invisibility means calls to debate and re-examine those assumptions are difficult and overdue.

This needs to be born in mind when deciding what is required from inside spaces, especially in the face of increasing climatic extremes, and as millions of properties are in need of retrofitting for energy efficiency. Not only can existing homes be improved, and new ones built better, but the dial on 21-22℃ assumption on comfort could be turned down.

A 2012 study commissioned by the Department for Energy and Climate Change in the United Kingdom from Cambridge Architectural Research looked at potential energy savings from small behaviour changes. It concluded that turning down the thermostat on central heating systems yielded the biggest savings. Lowering by 2°C from 20°C to a moderate 18°C across the British housing stock would save the equivalent of 33 TWh of electricity. To put that into perspective it represents about two thirds of Portugal’s domestic electricity consumption in 2019 of 48 TWh.

There is currently huge demand for reducing the amount of energy used to heat or cool homes whilst also making buildings integral to renewable energy generation. Day to day energy use gives rise to what is known as “operational carbon emissions” and currently accounts for about 28 percent of global emissions annually. A huge increase in the rate of existing building energy efficiency is required to meet emissions reduction targets set by the Paris Climate Agreement. But building renovations currently affect only 0.5-1% of the existing building stock each year. Governments are variously funding schemes to insulate inefficient old buildings and to remove polluting systems such as gas boilers in favour of renewables. All these efforts are chasing the target of “net zero” carbon emissions and beyond to ‘negative’ emissions in which the carbon equation for energy generation becomes net negative – resulting in an overall reduction while occupying a building. For most older houses in particular, this process can be costly, disruptive and time-consuming to manage; without government assistance or incentives, few people are willing or able to undertake the challenge. But, even in countries claiming leadership on climate issues like the UK, progress has been slow.

But what if you could refurbish your home in a single week without moving out and without stumping up any extra cash? Enter the Energiesprong approach from the Netherlands, which offers just that by integrating refurbishment, regulatory change and financing that enables future savings to pay for current investment. This wraparound system relies on development teams to find suitable buildings – often working with housing associations – which are then clad externally and given renewable heating or cooling apparatus. After an Energiesprong retrofit, a home is net zero energy, meaning it generates the total amount of energy required for its heating, hot water and electrical appliances. They use new technologies such as prefabricated facades, insulated rooftops with solar panels, smart heating, and ventilation and cooling installations. The subsequent refurbishment comes with a long-year performance warranty on both the indoor climate and the energy performance for up to 40 years. And complete home makeover can be finished in less than 10 days, and some have been done in as little as a day.

It’s an approach that could become much more widespread. From Ireland to India, economic stimulus packages in response to the impact of the coronavirus pandemic are including spending on retrofitting both homes and workplaces and the Energiesprong approach could be taken up much more widely.

This fast and scalable solution needs to be set against the growth in global building space, which is set to double by 2060 if it continues at the current rate. More than half of the global population is now concentrated in urban areas, and by 2060 two thirds of the expected population of 10 billion will live in cities. To accommodate this tremendous growth, the equivalent of an entire New York City could be added to our global built environment every month for the next 40 years. Since the energy used simply to construct buildings before their use constitutes an additional 11% of global emissions today, it is vital that this new building stock must be designed to meet zero-net-carbon, or net negative standards.

Wider relevance

The Energiesprong system is particularly interesting because, although it works for single properties, it also looks at the regulatory environment and the supply chain as part of the wider construction environment. Market development teams work in all these areas in preparation for projects, to stimulate demand and design a possible pathway for scaling their refurbishments. They work with regulators to suggest fine-tuning for policy and regulation, and with banks to create financial arrangements that make it viable to work at scale. This gives suppliers the confidence to invest in off-site manufacturing of the components needed for such house makeovers; without mass manufacturing, these initiatives will remain niche and make little impact on the wider construction landscape or on emissions reductions. In the Netherlands, where the initiative originates, already it has developed further into a network known as Stroomversnelling. This consists of contractors, component suppliers, housing providers, local governments, financiers, DSOs (energy system managers known as ‘distribution system operators’) and other parties. Its objectives are to reduce the renovation costs of net zero carbon refurbishments, increase occupants’ acceptance of such renovations and increase the pace of growth in the net zero carbon housing market itself.

An Energiesprong renovation or new build is financed in an unusually forward-thinking and long-term way. The budget is taken to be future energy cost savings plus the cost of planned maintenance and repairs over the coming 30 years. The idea is to keep residents or householders’ bills at the current rate by spreading the cost into the future, when energy bills will be lower. In the case of housing associations, the housing association foots the bill for conversion and the tenants pay the housing association back via an energy service plan set at a similar rate to their previous energy supplier bill. The housing association can then use this new income stream to partly fund the renovation works. Typically, legislation needs to be amended to allow housing associations to convert a monthly energy bill into an energy service fee. Most changes to renewables require significant capital expenditure which people which people either do not have, or do not wish to spend on energy reduction. This enables them to plan into the future at a steady rate without paying up front, while knowing that their carbon footprint is shrinking – and is a model that could be replicated elsewhere.

Context and background

To meet the goals of the Paris Climate Agreement, which aims to limit global temperature rise to 1.5℃, the built environment’s energy intensity—how much energy a building uses—will have to improve by 30 percent by 2030, according to UN Environment. Globally, the energy intensity of the building sector is improving by about 1.5 percent every year with new technologies, fuels and materials; however, this is being more than offset by the number of buildings. Global floor area grows by about 2.3 percent annually and carbon emissions related to buildings are expected to double by 2050 unless action at scale takes place.

Making houses less demanding of energy is also a social justice issue. Of the British domestic properties which have registered an energy efficiency rating, only 0.05 percent of existing dwellings and one percent of new builds are in the highest band A – and most are intricate one-off designs to be kept temperate with almost no heating or air conditioning. But most of the housing stock – and particularly rental properties and those in poorer areas, are leaky and cold, and can become damp when insulation is added without care for ventilation. Many people simply cannot afford to heat them. In the tragedy of the Grenfell Tower block fire in London three years ago, 72 people died when unsafe – and recently added – external insulation caused fire to spread quickly throughout the tower block. Some 246 buildings in the UK still have the same Aluminium Composite Material (ACM) cladding today. Meanwhile, that same winter in London, deaths from cold homes were estimated at 17,000. One attempt to give poorer people better access to high-tech renewable options is a solar project called Repowering London, whose world-leading work has already transformed communities by training local young people to  install  photovoltaic cells on social housing blocks by local young people.

Energiesprong originated in the Netherlands, where it began as a government-funded innovation programme to drive an improved energy efficiency standard in the domestic market. Today, over 5000 homes in the country have been retrofitted to net zero energy houses at no extra costs for the residents and a further 9000 are planned. Currently, there are Energiesprong initiatives ranging from the Netherlands, to France, the UK, Germany and Northern Italy. In the US, groups inspired by Energiesprong are working on a solution for their own markets in New York State (RetrofitNY) and California.

Pilot projects have been done often in partnership with local councils, such as Nottingham City in the UK, which is aiming to be the first carbon neutral city by 2028. The proof of the system at the single house and group of single house levels has inspired them to look now to converting apartments led by the French project.

The UK, France, Germany and the Netherlands alone have 43 million apartments that are not future proof because there is no viable deep energy retrofit solution available yet for these buildings. Under the “Mustbe0” European programme, market development teams in the four participating countries will work specifically on solutions to fit apartment buildings in North West Europe. Nine housing providers have already committed to collaborating on the retrofit of at least 9 demonstrator buildings (with a total of 415 apartments) in the UK, France, Germany and the Netherlands within the Mustbe0 programme.

Enabling factors

The speed of Energiesprong’s approach is due partly to their collaborative method of working alongside existing partners to develop a marketplace. A firm understanding of where to go for funding and the model of spreading the repayments into the future also helps. For instance, in London, Energiesprong is one of the key partners in the Mayor’s Energy for Londoners programme, which is designed to speed up the pace of cutting carbon emissions and achieving zero carbon by 2050. With the backing of the European Regional Development Fund, the Retrofit Accelerator for homes will help tackle the climate emergency and reduce energy bills, by installing insulation and low carbon heat and power solutions. The £3.6m programme is funded on a 50:50 basis by the Mayor of London and the European Regional Development Fund (ERDF).

The aim is for this programme to provide London boroughs and housing associations with the technical expertise they need to kick-start ‘whole-house’ retrofit projects across the capital. It will also help build the supply chain and business case to accelerate the retrofit revolution for private homes.This will mean new jobs too – something that is increasingly badly needed as we build back from the Coronavirus. London’s homes are responsible for around one third of the city’s greenhouse gas emissions and a quarter of them have the worst energy performance rating. This year, Londoners will spend approximately £3.5bn powering their homes, pushing almost 12 per cent of them into fuel poverty. The programme is currently planning 1,600 whole-house retrofits in Greater London over the next three years. It may be possible for these alterations to be scaled up, given recent government plans to offer £2 billion in grants for making homes more energy efficient – however, such schemes are often ringfenced and not available for partnership with existing schemes such as Energiesprong.

It is interesting that in the example of the UK in particular, action has been taken at the city level rather than by county or national government. We have seen this sort of municipal initiative in movements such as the C40 pledge to make all new buildings zero carbon – so far, 25 cities around the world have signed up. Cities like San Jose and Berkeley in the US are banning gas installations in new residential construction. New York City recently passed a slate of new bills in its Climate Mobilization Act, which calls for building retrofits to achieve a 40 percent decrease in greenhouse gas emissions by 2030.

Scope and evidence

• To meet the goals of the Paris Climate Agreement, the built environment’s energy intensity—how much energy a building uses—will have to improve by 30 percent by 2030, according to UN Environment.
• This day to day energy use to run buildings currently accounts for about 28 percent of global emissions annually.
• Building renovations currently affect only 0.5-1% of the existing building stock each year.
• Energiesprong is a ‘whole house’ system where development teams find suitable houses – often working with housing associations – which are then clad externally and given renewable heating or cooling apparatus. It originated in the Netherlands, where it began as a government-funded innovation programme to drive an improved energy efficiency standard in the domestic market.
• Today, over 5000 homes in the country have been retrofitted to net zero energy houses at no extra costs for the residents and a further 9000 are planned. Energiesprong teams are active across Europe and have inspired spin-offs in the US too.
• After an Energiesprong retrofit, a home is net zero energy, meaning it generates the total amount of energy required for its heating, hot water and electrical appliances.They use new technologies such as prefabricated facades, insulated rooftops with solar panels, smart heating, and ventilation and cooling installations.
• The subsequent refurbishment comes with a long-year performance warranty on both the indoor climate and the energy performance for up to 40 years.
• And complete home makeover can be finished in less than 10 days, and some have been done in as little as a day.
• Global building space, which is set to double by 2060 if it continues at the current rate.

References

• Bell, A. 2019. The Ecologist. Life beyond energy bills. https://theecologist.org/2019/aug/22/life-beyond-energy-bills
• Heather Chappells & Elizabeth Shove (2005) Debating the future of comfort: environmental sustainability, energy consumption and the indoor environment, Building Research & Information, 33:1, 32-40, https://www.tandfonline.com/doi/pdf/10.1080/0961321042000322762
• Climate Change Committee (2020) t Reducing UK emissions: 2020 Progress Report to Parliament
• Architecture 2030: Why the building sector? https://architecture2030.org/buildings_problem_why/
• Budds, D. 2019. Curbed. How do buildings contribute to climate change? https://www.curbed.com/2019/9/19/20874234/buildings-carbon-emissions-climate-change
• Energiesprong https://energiesprong.org/energiesprong-starts-innovation-project-for-apartment-buildings/
• Fanger, P.O. (1970) Thermal Comfort. Technical University of Denmark, Laboratory of Heating and Air Conditioning, Danish Technical Press, Copenhagen.
• Towards a zero-emission, efficient, and resilient buildings and construction sector: Global Status Report 2017
• https://www.worldgbc.org/sites/default/files/UNEP%20188_GABC_en%20%28web%29.pdf