The European Commission estimates that almost 75 per cent of Europe’s building stock is energy inefficient, with a renovation rate of just 0.4 to 1.2 per cent per year, depending on the country. But several projects are racing to overcome the many hurdles to improving this. These hurdles are technical, economic, social and regulatory.

Energy jump

Energiesprong (“Energy jump”) is probably the most successful European nZEB retrofit project. It has been involved in refurbishing over 5000 homes across Europe, with over 20,000 more in the pipeline.

The majority of these are in the Netherlands, with the next highest number in France, in the UK, Germany and Italy respectively.

Tenants no longer receive energy bills and the buildings have a 30-year performance warranty on both the indoor climate and the energy performance.

Because the external installations are fabricated offsite and installation is efficient, work on site generally takes less than 10 days.

It’s been helped partly because the construction sector has shown sluggish activity in new build and sees an opportunity to develop new skills and markets.

Energiesprong recently won a first prize in the 2019 UK Ashden Awards, whose assessors applauded its potential to radically cut carbon from the housing stock by refurbishing older hard to heat homes, both faster and in higher numbers, welcoming progress in cities such as Nottingham and Maldon, Essex.

In the UK a total of 186 net zero energy retrofits are now confirmed with 155 further Nottingham households due to benefit this year.

Ashden commented: “Energiesprong holds huge promise because it can scale. With industrialisation, costs come down, retrofits get faster and further quality gains become possible. As we move towards a zero-carbon society we can then really look forward to everyone living in a desirable, comfortable home that is affordable to heat.”

Emily Braham, Energiesprong UK’s Head of Team, said: “There are 11 million homes in the UK we could retrofit to Energiesprong’s net zero energy standard with today’s technology. Working with the National Energy Foundation on the European Transition Zero and E=0 projects has helped us build significant demand for a model which we’ve shown can work, with front-running landlords who own more than 100,000 homes.

“At 40,000 homes per year costs will reduce to make the retrofit self-financing, which we are targeting by 2030.”

The Nottingham homes before and after their Energiesprong refurbishment (some in the picture chose not to participate).

Rapid acceleration

Energiesprong’s success depends partly upon brokering a so-called “Stroomversnelling” (“Rapid acceleration”) deal between building contractors and housing associations.

Stroomversnelling is now supporting Energiesprong teams in France, the UK, Germany and New York State. It works because it deals in large volumes of similar types of building.

The cash that previously went on energy bills and maintenance pays for the upgrade. The whole operation is cost neutral, and perhaps make a profit on export of surplus energy.

Stroomversnelling has just announced a new form of contract for guaranteeing 100 per cent energy performance for zero-meter homes, in both the renovation and the new construction markets.

Under this agreement, the provider has to be responsible for the management of the installations on the maintenance of the buildings for at least 10 years during which time it guarantees that the agreed energy performance level is reached.

This agreement is the result of years of practical experience on the ground.

The HEART of the matter

Another important effort to overcome the hurdles to mass roll-out of deep-energy retrofits is focused on southern Europe.

“Business models and solutions are not entirely there yet, in terms of cost and quality,” Sébastien Garnier, innovation and project manager at Housing Europe, told REVOLVE in an interview. Housing Europe is a representative network of social and public housing organisations whose members manage about 11 per cent of households in Europe.

He is working with 15 partners in the Horizon 2020-funded Holistic Energy and Architectural Retrofit Toolkit (HEART) project consortium.

The HEART project is developing a retrofit toolkit to transform such buildings into smart, low-energy homes and offices.

It is funded by the extremely ambitious European Horizon 2020 program. This year H2020 is investing €11 billion across the board in new solutions for societal challenges including a low-carbon, climate resilient future: €3.7 billion; circular economy: €1 billion; and digitising and transforming industry and services: €1.8 billion.

“Although HEART’s holistic approach relies on energy systems automation, algorithms and smart appliances, it is all about the people,” Garnier says.

HEART is a cloud-based decision-supporting system. It seeks to improve the business case for retrofit by identifying the optimum combination of low-carbon tech and operational management for a given building.

The components of the HEART system

“This is a holistic package, that combines all the different elements – photovoltaics, renewables, insulation – for deep renovation, and that can help to choose the most optimal mix and settings. A test case of ways to get the best value, in terms of energy performance and investment costs,” Garnier told REVOLVE, a web portal.

It uses a predictive energy model that incorporates local climate details to optimise solar gains for heating or a building envelope’s thermal mass to reduce both summer and winter energy use for heating and cooling.

The model has the ability to learn from its own experience using feedback from continuous building monitoring and from the users.

A minimum number of strategically positioned sensors measure temperature, relative humidity, occupancy, CO2, etc.

components of the HEART computer model

Two social housing buildings are acting as guinea pigs for the system. They’re managed by Est Métropole Habitat in Lyon, France, and ACER in Reggio Emilia, Italy. The goal is for both of them to reach nZEB levels of energy consumption (<50 kWh square metre a year  with energy savings of 90 per cent.

Such buildings are typical of the market HEART is targeting in Central and Southern Europe: medium-size, multi-storey condominium buildings, constructed in the second half of the 20th century in moderate climatic zones. There are probably around 1 million like these in Europe.

Garnier distinguishes between different types of buildings and occupiers with different needs: homeowners of single-family dwellings, homeowners in apartment blocks, tenants renting from private landlords, and tenants renting from professional social, public, cooperative or private housing providers.

He says that the first three groups “need much more intensive support in terms of skills and finance to undertake deep renovation, and that in these sectors one-stop-shop service offerings are emerging, often driven by local authorities.

He thinks this is about social innovation – “basically, organising and motivating people. The technical aspects, and incorporating new types of tailor-made financial packages, will be key to get the market moving.”

In the fourth group, the social and public housing market, it is the owner or landlord who takes the decision to renovate. Although these people are professionals, “further financial innovation [is] needed for this sector too,” to prevent them from going into debt (at least on paper) as a result of the investment required.

To tackle this issue, one option is to let an ESCO (energy service company) take on the debt, but in the end this will be more expensive than doing it themselves.

A better solution would be to change the regulations to allow public investments for such societal and environmental long-term investments, says Garnier, especially where it is clear there is a business case with a financial payback, that is energy, climate and health savings and benefits.

The social, security and regulatory boundaries and ways to overcome them are examined in a recently published self-critical report from HEART.

Garnier believes that involving tenants closely throughout the whole process is vital to the success of the operation to reduce their fears, allay misconceptions, minimise hassle.

In the future, there will be many different models offering to retrofit the millions of buildings that need it.

The complexity of the challenges makes it harder to catalyse the process than a simple market stimulus like the feed-in-tariff that boosted the take-up of solar photovoltaic panels in buildings.

For this reason it is unlikely that the world will get a straightforward Uber or AirBnB type solution to deep retrofit, but the rewards will still be great for the partnerships that ultimately crack it at scale.

David Thorpe is the author of Passive Solar Architecture Pocket Reference, Energy Management in Buildings and Sustainable Home Refurbishment.

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