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Periodic Reporting for period 2 - TRANSITION ZERO (Make Net Zero Energy refurbishments for houses a mass market reality)


The EU has set itself a long-term goal of reducing CO2 emissions by 80% when compared to 1990 levels, by 2050. The implication of this is that the existing European building stock needs to be at least near net zero energy by the mid-century. However, with an expected 80% of...


The EU has set itself a long-term goal of reducing CO2 emissions by 80% when compared to 1990 levels, by 2050. The implication of this is that the existing European building stock needs to be at least near net zero energy by the mid-century. However, with an expected 80% of the existing building stock still being in place by 2050, this level of refurbishment is difficult to achieve in the current market due to the cost and the disruption to existing occupiers. Most of the refurbishment happening today is done on a piecemeal basis, without any long-term performance warranty. These piecemeal improvements happen slowly, often creating both technological and financial lock-outs for further improvement which means it is impossible to achieve what is needed to reach our long-term goal.

Achieving near net zero energy consumption using the Energiesprong standard in existing buildings is an important part of reducing existing levels of greenhouses gases thereby avoiding the devastating consequences of climate change. Carrying out whole house retrofits reduces energy bills for occupants, enabling them to live in warmer, more comfortable homes. An additional benefit is the regeneration of existing areas. Homes are given an improved look and can be modernised internally, which is of benefit to all those living in the vicinity and adds consumers appeal, which is needed as most of them have only limited interest in investing to reduce CO2 emissions.

The overall objectives of Transition Zero was to facilitate volume commitments for the near net zero energy refurbishment in the UK and French markets and build a pipeline of demand plus creating more demand for net zero energy retrofits in the Netherlands, where the Energiesprong approach had already made a good start. Transition Zero achieved this through creating a viable refurbishment proposition for social housing organisations, financiers and governments. It also challenged the construction sector to start an ambitious innovation process to deliver what is needed.

Work performed

The following work was carried out during the course of the Transition Zero project:

• Setting up Market Development Teams in France and the UK (WP1)
• Assessing financing options for UK and French markets (D2.2)
• Developing a performance specification for Energiesprong retrofits (D2.3)
• Developing and testing procurement and contracting templates for Energiesprong standard retrofits (D2.4)
• Developing and implementing an urban infill proposition and performance contract in the UK market (D2.5)
• Assessing the French and UK regulatory framework (D3.1). As well as making recommendations for decision makers (D3.3)
• Defining an Energiesprong standard retrofit package. (D3.2)
• Analysing financing for pilot projects (D4.1) and a structured finance product (D4.3)
• Optimising the UK and French business case, that turns long term (30-40 year) maintenance and energy costs into productive net zero energy investment (D4.2)
• Defining the structure of the performance guarantee and development of a template delivery protocol for Energiesprong standard retrofit (D5.1 and 5.2)
• Supporting the demonstration of Energiesprong standard retrofits in the UK and French markets (D6.3)
• Gaining collective commitments for the next wave of scale from social housing providers in the UK and France (D6.1 and 7.2)
• Brokering contracts for Energiesprong standard retrofit within the Dutch, French and UK markets (D7.1 - 7.4)

As a result of Transition Zero in the UK, 10 homes were retrofitted to the Energiesprong standard by one social housing provider (Nottingham City Homes). 185 housing units were contracted (155 Nottingham City Homes, 15 ZEBCat consortia, 5 Moat Homes), 46 are in procurement (Sutton Housing Partnership) and a further 12 funded (Cost to Capital consortia) - totalling 243 demonstrators. In addition, 4 social housing providers, managing 77,500 units (Nottingham City Homes, One Manchester, Sutton Housing Partnership, and Stonewater) have signed a collective commitment to bring a further 647 units to the market. These form part of a pipeline of 21 housing providers managing c350,500 homes. 64 supply chain providers were engaged, 3 solution providers are active (Melius Homes, Midas Mi Space and Engie), one of which (Melius Homes) is industrialising.

22 homes (10+12) in France were retrofitted to the Energiesprong standard by 2 social housing organisations. A tender call for 988 Energiesprong-ready home retrofits in collective social housing in Lyon was contracted. Néotoa, procured a project (4 dwellings) near Chateaugiron. Vilogia tendered 160 dwellings in Wattrelos. 14 social housing organisations, signed a non-binding 6,550 home volume deal, along with 37 solutions providers and 13 facilitators.

In the Netherlands a soft commitment for 15,000 home retrofits was achieved with two major social housing companies (Elkien and Accolade) and three solution providers (van Wijnen, Jorritsma and Dijkstra-Draaisma). Smaller implementations followed. Over 30 social housing companies were supported, collectively completing over 3,500 retrofits over the course of the project, of which 1,748 were built in 2018 with a scheduled additional project pipeline of over 1800 retrofits to be completed in 2019 amongst these housing companies. The Dutch market is world leading in volume for off-site manufactured, performance guaranteed, net zero energy retrofits and drives other EU markets. Demonstrated by the movements and collective agreements in France and the UK, as well as the subsequent development of the German and Italian markets (funded by other sources outside of the Transition Zero project).

Final results

Progress beyond the state of art achieved as a result of the Transition Zero project are:

• Energy performance contracting for homes established in France and the UK

• Early market demonstrators and roll out: France and the UK market development proved that Energiesprong standard net zero energy retrofit can be replicated outside the Netherlands

• Quality assurance and monitoring in the UK and France: new quality assurance, monitoring, reporting and contracting approaches proved robust, identifying where the solutions were performing, underperforming and enabling remedial action

• Quality assurance and monitoring in the Netherlands: a new high-quality industry standard, NOM-Keur, was established which assures the quality performance at design, build and in-use stage (

• Net zero energy standard for urban infill: on the back of the market development of net-zero-energy retrofits, there is now also strong growth in the market for Energiesprong standard urban infill which was accelerated in the Netherlands by legislation passed in September 2017 to enable an energy performance charge

Socio-economic impacts

• Environmental (e.g. carbon savings) and social benefits (e.g. benefits to tenants in living in warmer, more comfortable homes, neighbourhood regeneration etc.) will be experienced at scale as more homes benefit

• Anecdotally, tenants in France and the UK report improved living conditions. Analysis of results from a questionnaire to French, UK and NL consortia and tenants is anticipated after the Transition Zero project

• SME impact: In the UK, two active SMEs entered the market (Melius Homes (a start-up) and Midas Mispace). In France, a consortia of SME’s responded to a procurement exercise.

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