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‘Comfortable Living Environment and Energy Reducing Homes’

(funded by Northern Ireland Energy Agency)

The CLEVER Homes project commenced in November 2004. It is a cross-border partnership project aimed at demonstrating two types of solar-powered ventilation technologies combined with energy efficiency measures in homes throughout Northern Ireland and the Republic of Ireland. The intention of the project is to enhance indoor air quality, reduce domestic energy consumption and bills and improve the health and quality of life of the householders. The Research Team has evaluated the project’s outcomes to date.

The report launch

The report launch

Launch event for the CLEVER Homes evalutation report

The final evaluation report for CLEVER Homes, prepared by the Research Team, found that the ventilation systems had improved indoor air quality, reduced mould and condensation and improved the health and wellbeing of householders. The report was launched in October 2007 at an event in County Cavan, RoI, where Sarah McLean presented a summary of the report’s findings. The event was well attended by Government officials involved in energy, health, housing and fuel poverty in Northern Ireland and the Republic of Ireland. Please click here to see Sarah’s presentation. Below is a summary of the report and its findings.


The CLEVER Homes project aimed to demonstrate two types of solar ventilation technologies – Nuaire Drimaster Ecosmart and Sunwarm – combined with energy efficiency measures in homes throughout Northern Ireland and the Republic of Ireland (RoI). The intention of the project was to enhance indoor air quality, reduce domestic energy consumption and bills and improve the health and wellbeing of the householders. The Ecosmart and Sunwarm systems are positive input ventilation systems that gently supply tempered filtered air into the home, replacing old contaminated, vapour-laden air. Both systems can use solar energy to warm the air entering the home. They can also provide cooler air to the home if needed. The systems draw air from outside the home, within the roof space, beneath the roof tiles (Ecosmart) or through two roof-mounted solar collectors (Sunwarm). The main difference between the two systems is that the Sunwarm system has two roof-mounted solar collectors installed, which enables this system to also provide some solar water heating. In addition to the ventilation systems, participants in the CLEVER Homes project were offered cavity wall insulation, top-up of loft insulation and low energy light bulbs. Both the ventilation systems and the energy efficiency measures were heavily subsidised for all participants in the project.


Twenty-two per cent (26 homes) of participant households in Northern Ireland were monitored before and after installation of the systems for changes in temperature, humidity and air pollutants (benzene, formaldehyde and nitrogen dioxide (NO2). There were three periods of monitoring: pre-installation, one month post-installation, and six months post-installation. In addition, changes in energy consumption were assessed by sending a questionnaire to all of the monitored homes asking for records or estimates of heating fuel consumption before and after installation of the ventilation system. Electricity records were also provided by NIE for the monitored homes. Almost all participants in Northern Ireland were surveyed prior to and after installation to assess health and wellbeing impacts of the systems and impacts on energy consumption. A final questionnaire was sent to all participants to assess their level of satisfaction with the project and its components.

Results and conclusions


Benzene, formaldehyde and NO2 are all common indoor air pollutants that can cause adverse health effects, ranging from irritation of the eyes, nose and throat to more serious illnesses such as cancer. Common indoor sources of these pollutants are cigarette smoke, gas fires and cookers and household products and building materials (for formaldehyde).

There was little difference in performance between the two ventilation systems for all of the monitored factors. Air quality improved in all of the monitored homes, with a significant reduction in both benzene and formaldehyde levels following installation of the ventilation systems. This is likely to have health benefits for occupants because formaldehyde levels went from being above WHO guidelines pre-installation to safe levels post-installation. There is no safe level of exposure for benzene because it is carcinogenic and therefore any decrease in benzene is beneficial for the health of occupants. However, there was still scope for further reductions in benzene in monitored homes. Although NO2 levels were not reduced post-installation, they were always at a level that did not present a health risk.

Temperature and relative humidity

Living in cold, damp, mouldy homes presents a risk to human health. High indoor humidity can lead to mould growth and also promotes the growth of house dust mites, the faeces of which are highly allergenic and have been linked to asthma.

Monitoring as part of the CLEVER Homes project showed that monitored homes maintained indoor temperatures at or above the 16°C temperature recommended by health guidelines, both before and after installation of the ventilation systems. In addition, more households were happy with the temperature of their home post-installation. The humidity data showed that use of the ventilation systems did not provide indoor relative humidity at sufficiently low values to avoid growth of house dust mites and in a few cases, relative humidity might also be high enough to support the growth of moulds. Despite this, the ventilation systems have been effective in reducing mould growth, condensation and damp for the majority of households, as evidenced by the results of the health surveys.


Results from the health surveys suggest that the ventilation systems have led to improved mental and physical health of participants and their children, with a significant reduction in householders suffering from asthma, asthma attacks and wheezing or whistling in the chest. There was also a significant reduction in visits to the doctor by participants and their children following installation of the systems. Improvements in health are most likely linked to the improvement in air quality (from the reduction in formaldehyde and benzene) and the reduction in damp, condensation and mould attributed to installation of the ventilation systems.

Energy use and CO2 emissions

According to the manufacturer, the Ecosmart and Sunwarm systems have the potential to save 830 kWh/year and 3300 kWh/year respectively. This is because the ventilation systems supply the home with heated air during the heating season and fresh outside air during the summer season. An additional solar heat exchanger installed in the Sunwarm system provides domestic hot water, providing up to 50% of a household’s annual hot water needs. The systems reduce the need for householders to use other forms of heating and cooling, which usually would have been supplied by more carbon intensive fuels.

It is not clear from the results whether or not use of the ventilation systems led to a reduction in energy consumption and associated CO2 emissions in all households. However, the health surveys found that fewer households were worried about the cost of heating and fewer households had gone without heating due to cost, following installation of the ventilation systems, suggesting that participants were ‘comfort-taking’ in response to the new systems.

Learning points

Undertaking the CLEVER Homes project has resulted in several practical learning points, which can be used by other organisations undertaking similar projects:

  • At the start of the project, potential funding programmes and their criteria should be researched
  • All contractors should be appointed and roles, responsibilities, costs and timeframes agreed and documented
  • Requirements for building control and planning permission should be checked and any monitoring considered and planned
  • It is a good idea to undertake a small scale pilot before launching a full monitoring programme
  • If energy savings are being assessed for measures that are supposed to reduce heating energy demand, it is important to recognise the impact of ‘comfort-taking’
  • Monitoring participants need to be fully informed of what will be involved and confirm their willing to take part for the duration of the programme
  • The installation of technologies such as ventilation systems should be combined with advice on how the technology works, its benefits and how to maximise its performance (including advice on behavioural influences)

Policy recommendations

In recognition of the lessons learnt from undertaking the CLEVER Homes project and the benefits of the ventilation systems installed, it is recommended that policy makers consider developing further schemes that incorporate the installation of solar ventilation systems in existing and new-build homes in Northern Ireland and the RoI. It is also suggested that the possibility of incorporating solar ventilation systems as eligible measures under Warm Homes and Warm Homes Plus is investigated. In addition, it is recommended that policy makers support further research in this area, to follow-up the monitoring undertaken for CLEVER Homes and see if the results persist in the longer-term, and to assess whether there are solar ventilation systems, which are cheaper but provide the same benefits.

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