Rich data from wireless sensor technologies is helping track energy performance in sustainable construction and retrofitting initiatives.

A lack of understanding of how buildings behave in use, including those specifically designed to be energy efficient, has undermined the progress of sustainable construction and retrofitting initiatives. No-one knows if the measures have led to real energy-savings or not.

A lack of understanding of how buildings behave in use, including those specifically designed to be energy efficient, has undermined the progress of sustainable construction and retrofitting initiatives

Research has overwhelmingly shown that how a building is used is the critical factor, with up to 200% variation in energy consumption from identical buildings.

Evaluation of a building’s performance is not a common part of construction and commissioning, the assumption being that a building will perform according to the design spec. The shift towards sustainable building, as well as retrofitting campaigns, will be seriously undermined without clear and ongoing insight into how people and eco-buildings work together, and the steps that can be taken to ensure what is intended can be delivered in practice.

Information on behaviour will be a critical part of ensuring buildings are genuinely ‘resilient’, flexible and adaptable enough to deal with challenges from climate change, alternative use, and for the integration of new technologies without the need for major and expensive re-building. This kind of rich data will be important for Building Information Modelling (BIM), providing the basis for including an energy performance in-use dimension to the modelling.

Trials of new low-cost, wireless sensor technologies with the Orbit Housing Association have shown the potential for large-scale use of sensors a real option for closing the performance gap. New Wireless Sensor Networks have been developed that meet the needs of users in the built environment sector: low-cost, robust, easy to deploy and to interpret the data provided, and long network life on minimal battery power.

Intensive monitoring provides the opportunity for rapid insights into how any new technologies work, which are working and which are not. It is possible to identify precisely which technologies deliver the best value in terms of in-use performance, and to streamline procurement, feed back the learning into the future planning and design process and establish a stronger foundation of confidence in eco-friendly measures.

In the research, more than 200,000 items of data were generated from each sensor for every week of monitoring — tracking temperature, humidity, CO2 levels and VOC (Volatile Organic Compounds), compared against consumption of energy and water — and crunched into a form that can be analysed by non-experts. This way landlords can find out whether excessive carbon emissions are caused by the behaviour of residents, problems with heating systems or in the fabric of the building itself.

On the basis of the 70 homes monitored and analysed, Orbit has started making decisions on investment and areas for cost-savings. In one of the studies, the work has highlighted weaknesses in newly installed heating systems, which provided the evidence for calling back contractors for repairs.

It has also pointed at specific issues around occupier behaviour, which can now be addressed through information packs on the use of new technologies installed, the need for a site attendant to guide occupants and open house events for tenants to get help in managing their property. As a direct result of the research and work with Orbit, tenants have started to see savings of £250 per year in energy costs. In a survey of experiences, and despite the recent increases in levels of charges, 75% of tenants said they were satisfied with the size of their energy bills.

Orbit has saved £100,000 by identifying early some defects in the Passiv home site.

Energy performance in-use data will be important for the development of BIM as standard practice, with the potential for delivering cost-savings for developers and landlords over the full life-cycle of buildings.

Professor Elena Gaura is from the Low Impact Building Centre, Coventry University