How to properly ventilate airtight, energy efficient retrofitted housing is a challenge that Industrial Ph.D. Candidate Christopher Just Johnston from NIRAS works to solve via an exchange stay at China’s leading technical university in Beijing
Master of Science in Engineering Christopher Just Johnston from NIRAS is currently doing research amongst 35.000 elite students at Tsinghua University (THU) in Beijing, China.
The university is known for being one of the leading technical universities and has around 1000 applicants for every opening.
Christopher is on exchange as part of his Ph.D. His project is about how building energy and indoor climate relate to one another.
“I am researching how to implement ventilation systems in connection with energy retrofits of older Danish multi-storey housing,” says Christopher.
The focus of the study might seem bit narrow, but it will also be possible to use the acquired knowledge in new constructions, such as office buildings or various housing projects.
The indoor climate is still suffering
A lot of people believe that as long the demands of building regulations are met there will not be problems related with low ventilation rates or bad air quality. But that is actually not true:
“We still see buildings with bad indoor environments, even though they live up to regulations,” says Christopher.
One reason is that the requirement to increase insulation thickness has caused new and energy efficient buildings to be very airtight. When conditioned, polluted air cannot escape to the outdoors any longer, fresh air cannot enter into a building either. This can be bad for the indoor environment.
“Energy retrofitting of housing has been single minded – bringing down the costs of heating has been the only focus,” says Christopher.
Energy retrofitting is often done by re-insulating outer walls and ceilings, by replacing windows and closing cracks and crevices ensuring that less heated air can escape the indoor environment.
“Which is what we are trying to achieve. However, an unfortunate consequence of this strategy is that it also means that less fresh air gets into our homes, unless we actively add ventilation as part of the retrofit,” says Christopher.
This means that all the sources of pollution there are in a home, that are not appropriately dealt with during a retrofit, will become more dominant after a retrofit than they were before – proportionally so.
"You could say that if you halve the amount of fresh air intake, then you double the concentration of pollution in the indoor environment," says Christopher.
The Ph.D. project is about how to avoid the issues that can arise when renovating a building without thought for the indoor climate.
"My work consists of collecting information on why we do what we do in order to make better decisions in the future. It is a continuous process which we are constantly working on," says Christopher.
Converting research to business
The project is an Industrial Ph.D. and is being conducted as a cooperation between the Technical University of Denmark (DTU) and NIRAS.
NIRAS is paying part of Christopher Just Johnston’s salary and Expertise Director Peter Noyé is looking forward to NIRAS converting the research into business and a competitive advantage.
"Going forward, establishing reasonable ventilation will be in demand. In order to avoid half measures in energy retrofits, we have to find solutions to the problems we have with low ventilation volumes that will help facilitate delivering the required reductions in energy demand while at the same time ensuring that end users are happy and healthy. Consultants such as NIRAS exist in an industry of knowledge, and competition demands that we, as well as our competitors, keep improving," says Peter Noyé.