Older systems can work just as well as new ones

Why fixate on how old a ventilation system is? What really matters is how well it works. “Modern technology is no guarantee of a good indoor climate. It’s how the finished system performs that counts,” says Mari-Liis Maripuu, PhD, of CIT Renergy AB.

The consultancy CIT Renergy works with energy and indoor climate issues. Mari-Liis Maripuu is Business Area Manager for Indoor Environment. CIT Renergy is a subsidiary of Chalmers Industriteknik.

“I lead a team that works with indoor climate issues in buildings, but also in industry,” she explains.

She believes the industry is developing rapidly and that it is important both to keep up with that development and to contribute to it. She holds a PhD in building services engineering from Chalmers and is passionate about demand-controlled ventilation.

“The purpose of demand control is to ventilate exactly as much as needed – no more, no less – while saving energy. This is done by automatically regulating airflows in the room based on measurable factors such as occupancy, carbon dioxide levels and temperature. The basic principle is simple: the right amount of air in the right place at the right time. The more the number of occupants in a room varies, the greater the benefit of demand control,” says Mari-Liis Maripuu.

Focus on function

But demand control is not suitable everywhere. So how should you approach improving ventilation while also saving energy?

“My most important advice is to start by looking at function rather than technology. Find out how the ventilation in your building works today and make sure the right amount of air reaches the right place at the right time, without causing indoor climate problems such as noise and draughts. Then you can decide what measures are needed to improve the indoor climate while saving as much energy as possible.”

She stresses the need to start from what ventilation is actually for: removing air pollutants and supplying fresh air. There are various ventilation principles, ranging from natural ventilation to mechanical systems with balanced supply and exhaust air and heat recovery.

“All principles have their pros and cons, but the most important thing is to make sure the functional requirements are met. An old system can work well, and a new one can work less well. Modern systems offer better ways to control airflows, supply air temperature and energy use. But modern technology doesn’t solve everything on its own. Modern systems must be properly designed, installed, balanced and operated. You need to keep track of the airflows, but the placement of supply and exhaust air terminals is also important. Otherwise, even a modern system can cause indoor climate problems such as poor air quality, draughts and noise,” she says.

Look at the big picture

Switching from a simple exhaust air system to a modern supply and exhaust air system is not always possible or cost-effective.

“Modern ventilation systems are highly energy efficient thanks to heat recovery, efficient fans and advanced controls. At the same time, they can be difficult to install in existing buildings, especially in apartment blocks, where there is often no space for ducts and air handling units. But even in buildings with exhaust air systems, there is often room for improvement. More energy-efficient fans, better controls, correct balancing and, in some cases, heat recovery from the exhaust air can deliver both a better indoor climate and lower energy use. Modern technology offers better opportunities to create a good indoor climate with low energy use, but only if the system works as intended. In the end, it’s the function that counts,” Mari-Liis Maripuu concludes.