Energy Bill

Memorandum submitted by CALEBRE (EN 34)

Executive Summary

The ‘CALEBRE’ team welcomes the opportunity to respond to the Energy Bill Committee’s call for written evidence.

Project ‘CALEBRE’, ‘Consumer-Appealing Low Energy technologies for Building REtrofitting’, is a four year, £2m E.ON / Research Councils UK Energy Programme- funded research project. Its aim is to identify consumer-acceptable retrofit solutions to reduce the carbon impact of existing dwellings, particularly solid walled, "hard to heat" ones. The project runs from October 2008 to Sept 2012 and work is on-going. Based on emerging findings from the project, recommendations are given for the forthcoming Green Deal Policy and are summarised below:

· Consider occupant comfort as one of the metrics in the selection of energy efficiency measures as part of the Green Deal.

· Include both piece-meal and whole house refurbishment approaches.

· Acknowledge the importance of local professionals and SMEs in relation to consumer trust and satisfaction, when properties are refurbished.

· Allow scope to include technologies emerging from ‘CALEBRE’ such as advanced electric air source heat pumps, transition technologies like gas –fired air source heat pumps, and vacuum glazing, all of which could be capable of relatively easy retrofit application with reduced installation costs, time and disruption to householders.

· Review the extent to which the current national electricity grid network is capable of supporting a country-wide switch to efficient low carbon electric heating systems.

· Retrofitting of whole house ventilation heat recovery systems should be accompanied by improvement of air tightness to a minimum and/or desirable level, and identify and offer other inter-related measures jointly and not as stand-alone measures.

· Establish a quality control framework to ensure that works are carried out by certified installers and are inspected by certified inspectors upon completion.

· Try to ensure that Green Deal measures are conducted in the most appropriate order of retrofit depending on the characteristics of the property to maximize interim and long term energy and carbon savings.

· Develop a technology selection tool that takes into consideration customer appeal and acceptability, customised energy efficiency solutions for each type of property, generates the most appropriate order of retrofit and is inclusive for new emerging technologies.

Introduction to Project CALEBRE

‘CALEBRE’ is a £2million, four year research project jointly funded by E.ON and Research Councils UK Energy Programme. The project involves a partnership of six UK Universities: Heriot Watt, Nottingham, Oxford, Ulster, Warwick, and is led by Loughborough.

The project takes the approach of identifying, from a householder perspective, the barriers and challenges to the deployment of retrofit carbon-reduction technologies and then, from knowledge gained through householder engagement surveys, appropriately modify selected technologies for field-trialling, user reaction and thermal comfort evaluation. The selected technologies within the programme cover the range from fundamental to applied research, and include electric and gas-fired heat pumps, mechanical ventilation heat recovery (MVHR), vacuum glazing and innovative advanced surface treatments to control temperature and moisture via nano-technology. These technologies are being developed within the laboratory and most will be trialled in test houses for evaluation of their installation processes, performance, energy efficiency and thermal comfort. The E.ON 2016 house is one such test site built at the University of Nottingham and is a replica of a typical 1930s UK dwelling. Model development to support selection of bespoke packages of refurbishment measures is being pursued, together with mechanisms necessary for mass market roll out of technical solutions.

Emerging findings from some of the workpackages of ‘CALEBRE’, together with recommendations for the forthcoming Green Deal policy, are presented in the next section.

1.0 Emerging findings and recommendations

1.1 Motivation to carry out home improvements

In-depth qualitative surveys were conducted in 20 households (incorporating 66 permanent occupants) as part of the ‘CALEBRE’ project, exploring past home renovation work and attitudes to new energy-saving technologies. A more extensive householder survey is being planned during the next stage of the ‘CALEBRE’ project. Emerging findings indicate that people’s motivation to carry out refurbishment was not so much to save energy but rather the desire to improve comfort and the need to repair. Participants rarely mentioned energy as a motivator for making home improvements (despite knowing that the data collection was for an energy related project); instead issues relating to improved living conditions, reduced cost and more pleasant surroundings were cited as motivating factors for making significant changes to their homes. There was a desire to maintain and restore original features of the house like single glazed ‘character’ windows, for example, despite them being draughty and energy-inefficient.

Recommendation 1.1: That improvement of comfort (including thermal comfort) is considered as an important factor whilst selecting energy efficiency measures for inclusion in the forthcoming green Deal.

1.2 The r efurbishment process

Although many households undertook refurbishment works at the time of house purchase, ongoing improvements were carried out at intervals in a piecemeal manner. Very few homeowners were willing to move out of their property for refurbishment, unless there were health issues. Many householders were found to prefer carrying out improvement works themselves.

Recommendation 1.2: That the Green Deal package includes both a whole house retrofit approach and a piece-meal approach, in order to suit individual circumstances of households. Furthermore, a whole house approach may best be suited to when people are moving in after purchasing a house.

1.3 Whom do people trust to carry out home improvements?

Although many households did improvements themselves, the lack of knowledge of how to deal with solid wall properties and their character features was an issue .

When required, professionals were chosen on the basis of price, trust, recommendation and time that would be taken to carry out works, with unknown professionals generally not being given work. The same trusted professional s were used for variety of jobs, in preference to lesser known specialists .

Recommendation 1.3: That the Green Deal framework acknowledges the importance of local professionals and SMEs in relation to consumer trust and satisfaction and ensures that local professionals and SMEs are able to play a pivotal role in the delivery of the G reen D eal to householders.

1.4 Advanced heating solutions - electric based

Heat pumps that are currently available in the market tend to cause significant disruption to occupants as they require under floor heating systems to be installed or existing radiators to be resized and replaced to get higher efficiencies. The advanced air source electric heat pump that has been developed at the University of Ulster is capable of operating at higher efficiencies when used with existing radiators of a gas central heating system, thereby significantly reducing installation costs and disruption to householders. Currently, the time to install this heat pump is four hours. Costs of install were approximately £500 for 4 hours work including minor consumables of cable, trunking and pipework. Capital cost of the unit is estimated at £2500 at a volume production rate. Profit is not included in this figure.

Recommendation 1.4: That the Green Deal include technologies like the advanced electric air source heat pumps (when commercially available) that can be easily retrofittable, have reduced installation costs and generate least amount of disruption to householders.

1.4 Advanced heating solutions- gas based

Gas-fired air source heat pumps are being developed at the University of Warwick as part of the ‘CALEBRE’ project, and a prototype has been built and tested in the laboratory. The technology is completely novel and is ahead of products under development in Germany. The heat pump will be capable of operating with the existing central heating system. At 60 °C output temperature, COPs are in the range of 1.15 to 1.25, 30% better than that of a gas boiler. Complete penetration of this heat pump into the condensing boiler sector would save > 5% UK total emissions. Currently boiler manufacturers are keen on any COP > 1.2 at the right price and hence this heat pump promises to be a useful product. Exact figures are currently not available but it is expected to have a payback time of 3-4years for this heat pump. However, this heat pump is seen as a transition technology, as presently the national electricity grid low voltage local area network may not be able to sustain a UK wide switch to all-electric air source heat pumps.

Recommendation 1.4 a : That the Green Deal package of measures include ‘transition’ technologies like gas-fired air source heat pumps until the national electricity grid low voltage local area network becomes fully capable of supporting a country wide switch to electric heating systems.

Recommendation 1. 4b : That the Government undertake a review of the extent to which the current national electricity grid low voltage local area network is capable of supporting a country wide switch to efficient low carbon electric heating systems.

1.5 Advanced Vacuum Glazing

Around half of the current 26 million British homes are not properly insulated, resulting in significant heat loss through walls and windows. If conventional single and double glazing can be replaced with high performance vacuum glazing together with adequate wall and roof insulation, then a significant improvement in thermal performance could be achieved. Research teams at Ulster and Loughborough Universities are developing double and triple vacuum glazing with target U-values down to 0.33 Wm-2K-1 and with cheaper, better edge seals. Results from initial thermal characterisation tests of a section of fabricated double vacuum glazing (400mm by 400mm) has given a U-value of 1.26Wm-2K-1. Thermal modelling of a triple vacuum glazing system (three glass panes separated by two vacuums) has indicated a potential to achieve a U-value down to 0.26 Wm-2K-1.

Due to the narrow vacuum gap this glazing will only be 6-12mm thick depending on the number of panes used and could easily be used to replace panes in existing uPVC double glazing frames. The installation costs will be similar to installation costs for conventional double / triple glazing. The actual cost of manufacturing/supplying the glazing is still unknown. It is envisaged that in the longer term the cost of the vacuum glazing would have to be closer to conventional double/triple glazing. Perhaps a 20% premium could be charged.

Recommendation 1.5: That the Green Deal package of measures allows scope to include emerging technologies like advanced vacuum glazing systems that are not only more efficient than double or triple gazing but are cost-effective, easily retrofittable and improve thermal comfort by eliminating draughts and condensation.

1.6 Inter - related sets of measures

The ‘CALEBRE’ project installed a retrofit Mechanical Ventilation Heat Recovery (MVHR) system into an existing house that was being used as a test house. For the MVHR system to work effectively, there is a requirement for the building to be sufficiently airtight. Existing domestic buildings are generally fairly ‘leaky’, so installing an MVHR system alone will not suffice unless accompanied by suitable air-tightness measures. To investigate the level of air-tightness required, the ‘CALEBRE’ Project evaluated the performance of the MVHR system relative to successive sealing upgrades to the house. Air tightness levels at the test house were improved in four successive stages from a base case of 15.57 m3/m2/hr @ 50pa , to 14.31, 9.84, 8.6 and finally 5.0 m3/m2/hr @50pa, which is when energy savings from the MVHR were observed.

Recommendation 1.6: That whole house ventilation heat recovery be included as part of Green Deal energy efficiency measures and that such measures are accompanied by improvement of air tightness to a minimum and /or desirable level that is verified by measurement, to ensure energy and carbon savings are achieved . Further, the Green Deal should seek to identify and offer other such inter related measures jointly and not as stand-alone measures.

1.7 Quality control

Quality control will be absolutely essential in the success of the Green Deal. The experience of the ‘CALEBRE’ project with regard to this is as follows. Conventional draught proofing solutions have little impact unless installed correctly. We pressure-tested a test house before installing draught proofing and then immediately afterwards. The results showed little difference. However, we noted that poor installation was probably to blame and requested the installers to return and re-install their product under our guidance. The resulting better installation showed a considerable difference in pressure test results with a marked reduction in air leakage. Similarly, the ‘CALEBRE’ research team found that the MVHR system had not been well-installed. The system was not balanced and it pressurised the house, resulting in increased infiltration heat loss and reduced the MVHR efficiency by 10%. Furthermore, the performance of the system was reduced due to inadequate insulation on the body of the MVHR unit, poor duct work design and increased air leakages from diffusers that penetrated the ceilings with gaps.

Recommendation 1.7: That the Green Deal establishe s a quality control framework to ensure that works are carried out by certified installers and are inspected by certified inspectors, once completed.

1.8 Order of Retrofit

Project ‘CALEBRE’ has conducted a preliminary study to investigate the effect of varying the order of implementation of a series of retrofit technologies. Modelling was carried out to evaluate the energy saving potential of an ‘ideal’ order of retrofit, and a ‘non-ideal’ order of retrofit. Neither of these are necessarily the order in which householders undertake these measures, as parallel work surveying householder experiences suggests that many other factors govern the order in which retrofit is undertaken. Preliminary results from the investigation work carried out so far suggest that the retrofit process needs to take into account a number of factors beyond the immediate potential energy savings. This may necessitate a number of measures to be applied simultaneously, such as extensive draught-proofing and installation of mechanical ventilation with heat recovery (MVHR) and to ensure that the health of the occupants and quality of the internal environment of the dwelling are not compromised.

The results highlight that potential energy savings are more difficult to achieve as more measures are applied, therefore the corresponding return will be less for each individually technology as we progress through the retrofit process. Where loft and wall insulation achieve a 9% and 23% reduction in building energy consumption when applied early in the ‘ideal’ order, this decreases to a 7% and 17% reduction in a ‘non ideal’ order.

Recommendation 1.8: That various orders of retrofit are taken into consideration with respect to their intermediate and long term energy and carbon savings and that Green Deal measures are offered in the most appropriate order depending on the characteristics of the property.

1.9 Technology assessment tool

Two key barriers to the uptake of technological interventions designed to reduce energy and CO2 emissions of dwellings are (a) clarity of information and (b) ‘transactional exhaustion’. Unclear information presented to the householder could result in wrong choices being made, which in turn results in a series of transactions with installers and others as mistakes are rectified. What is needed is a single computational tool able to inform the householder of the package of measures needed for their home for achieving the required energy and CO2 reduction, and for this to contribute to a ‘one-stop-shop’ approach to the challenge of large-scale domestic refurbishment. Such a tool should take into account the uncertainties involved in predictions made and actual savings achieved in practice.

Starting with the computational tool developed by the TARBASE project, Project ‘CALEBRE’ is undertaking its further development to produce a desktop-based, computational tool that will take information about the dwelling, occupancy and location and output a tailored system package aimed at achieving emissions reductions. The new version will take into account the user perspectives as well as performance data about the technologies established from the laboratory tests and field trials. To date, this model now includes glazing, insulation, air tightness, occupancy, lighting, small power consumption, deployment of renewable energy generation and boiler replacement technologies. The data from the test houses is contributing to the verification of this tool, in particular, the relationship of air tightness with the operation of mechanical ventilation with heat recovery (MVHR). The model has also been used to better understand the effects of order of retrofit of energy-saving technologies in domestic dwellings.

Recommendation 1.9: That the Green Deal allows scope for a technology selection tool to be employed that takes into consideration customer appeal and acceptability, customised energy efficiency solutions for each type of property, generates the most appropriate order of retrofit and is inclusive for new emerging technologies.


This work forms part of the ‘CALEBRE’ Project which is funded by the Research Councils UK Energy Programme and E.ON, to whom the authors express their gratitude.


The work reported here was primarily carried out for academic purposes only. Recommendations presented in this report are based on findings to date from the ‘CALEBRE’ project and may change as further findings emerge during the course of the project. The authors of this report, university partners and the funders of the project cannot be held liable for the consequences of implementing any of the recommendations reported here. Any material presented in this report should be duly acknowledged when reproduced.

Prepared 22nd June 2011