#CIBSEsymposium 2019 content focus: In-use study of using Atamate building controls to improve heating efficiency
By Kat Kelly, Senior Data Scientist at Atamate
Modern building regulations emphasise the efficiency of building services, both to keep costs to a minimum and to limit greenhouse gas emissions. We conducted a real world study on the effect of Atamate building controls on energy efficiency.
The insulation and airtightness of modern building fabric has substantially cut heating energy requirements, allowing gas-powered central heating systems to be replaced with low-energy, fast-response electrical systems. In spite of the technological improvements, a 'performance gap' is often been reported between the energy efficiency predicted by the SAP model and the efficiency it achieves in the real world.
One reason is that energy models tend to assume that
everyone uses their home's building services as they're designed to be used. In
practice, stopping the kids' third fight of the evening is often a higher
priority than checking that the heating is switched off before opening a window
- which is likely to happen in a modern home because the well-insulated fabric
makes it prone to overheating.
Atamate controls continuously monitor temperature and air quality to operate the building services, leaving the occupants to focus on kids, TV or whatever else is uppermost in their mind. The system can be fitted to any type of building and can control everything from the entry gate to the garden sprinklers.
Our case study focused on the heating efficiency of 14 and 16 Cogan Terrace in Cardiff between September 2017 and September 2018. The two adjacent buildings were constructed to current regulatory standards and divided into six rental flats. The flats were heated by electric panels and infra-red heaters which were switched on based on two criteria: the room temperature fell below 21°C and the occupancy sensors detected someone in the room.
The plot below shows the heating in one of the bedrooms in mid-winter. The tenant was a student who returned to their parents' house for the Christmas break, hence the prolonged period with no occupancy. The controls wasted no energy heating the unoccupied room, but quickly heated it back to the 21°C setpoint when the tenant returned in early January.
Atamate also controlled the ventilation to maintain air quality. Kitchens and bathrooms were fitted with mechanical extract ventilation (MEV): extractor fans that were activated when required. Rather than losing all the heat energy to the streets of Cardiff, the fans ducted the exhaust air through a micro heat pump, which fed the heat into the hot water tank.
The bedrooms and living rooms of Number 16 Cogan Terrace were fitted with trickle vents while those in Number 14 used demand control ventilation (DCV): essentially similar vents but fitted with a valve under Atamate control. The plot below shows the DCV in action over two-hours in a bedroom. The Atamate sensors monitored carbon dioxide, temperature and humidity to generate an air quality index from 0 to -1 and adjusted the valve accordingly. It could be anywhere from fully open (100%) to fully closed (0%), though it only ranged from 25%-60% in the period covered here.
Something evidently happened at around 08:20 that affected the air quality, such as someone in another part of the building running a hot shower or cooking their breakfast. The control system responded immediately by opening the valve, which restored the air quality to its previous level within thirty minutes. If there was anyone in the room at the time, they probably didn't notice anything happening.
Overall, we found the heating efficiency of 16 Cogan Terrace exceeded the predictions of the SAP model, using 12% less energy than estimated. Number 14, which used DCV instead of trickle vents, did substantially better with a 34% energy efficiency improvement over the SAP prediction. The star performer was the top floor flat in number 14 which used, an impressive, 72% less energy than estimated.
We went on to compare our findings to the Passivhaus standard which mandates a maximum heat energy requirement of 15kWh/m2/yr. We found that both 14 and 16 Cogan Terrace fell below this threshold, even though no MVHR for space heating was installed and the current analysis did not factor in the recapture of heat energy for the hot water.
Passivhaus standards originated in Germany but our findings suggest that they may not be suited to the milder British climate. We found that in the UK, automated building controls offer similar or better efficiency without the need for PassivHaus design standards that typically add 20-25% to the cost.
This study shows that there is a great opportunity for controls systems, such as Atamate, to deliver excellent energy efficiency at a price point that will enable widespread roll out, and hence make a substantial contribution to a sustainable UK.
Our future studies will investigate that further by considering other domestic energy uses such as hot water, and by assessing the value of building controls in different types of building.
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See the 2019 Symposium programme and full event overview.
View CIBSE Journal for further Technical Symposium 2019 coverage.
A blogpost from Christian Guerra, Digital Engineering MSc student at University College London, sharing his student account of Kat Kelly's presentation, his personal Symposium highlight.
View CIBSE Journal for further Technical Symposium 2019 coverage.
A blogpost from Christian Guerra, Digital Engineering MSc student at University College London, sharing his student account of Kat Kelly's presentation, his personal Symposium highlight.
About CIBSE Technical Symposium
The CIBSE Technical Symposium is an annual event featuring speakers and poster presentations from a range of disciplines. All papers and posters are peer reviewed. Anybody can submit a topic for consideration, which will then be assessed by a panel of reviewers to determine its suitability.
Have you had a chance to chat to Kat Kelly? Join into the post-Symposium conversation @CIBSE I CIBSE Linkedin using #CIBSESymposium
Thank you to all CIBSE Technical Symposium 2019 speakers and reviewers.
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