Ventilation: forty years of development

Simple ventilation systems in housing estates made up the majority of Bemar's activities in the company's early days. "Well, perhaps you should not refer to them as 'simple', but the systems consisted of an MV box and some valves," says Jan.

Back in 1984, nobody had ever heard of heat recovery or self-regulating grilles. "The ventilation market took off in the mid-1970s," he looks back. "In residential construction, you saw more and more indoor toilets. These needed to have a supply of fresh air."

Mechanical extraction of toilet, bathroom and kitchen air quickly became the norm. This created negative pressure in the house, meaning that fresh air was drawn in. "We installed large numbers of these at Bemar, working on residential housing projects for major contractors and major building services companies in particular, as a subcontractor specialising in ventilation."

The fact that building services companies started outsourcing ventilation makes sense to Jan. "I've always stated it very simply: air is not the same as electricity, piping, bathroom plumbing or heating. And with time, air has become more and more of an area of expertise."

He sees that as the biggest change over the last 40 years: the development of the profession itself. Its growth from that basic mechanical ventilation system with valves into a whole array of ventilation options nowadays. With sensors for demand driven control, heat recovery - the range of options is now very broad. From the mid-1990s, this has been helped in part by regulations governing the energy performance of buildings: first the EPC, now BENG.

"Ventilation is an element you have to take into account nowadays if you want to achieve good energy performance for a building," Jan concludes. "Combined with things like insulation and glass. When we started, heat recovery was the exception, today we cannot do without it."

This has had an impact on the level of expertise required of the people who design, calculate and install the systems. Jan: “Of course it has. We as Bemar - and later also with all the other operational companies - were totally committed to mastering this market and its developments. We are one of the few companies that has taken all of this on board, that has upgraded the quality of their employees to the point where they can keep up with the modern market. For that reason, we are able to truly collaborate with manufacturers."

Quality manuals are a part of this. "That started out being fairly straightforward," says Jan, "but all kinds of requirements have been added on as well, such as maximum air velocity and noise transmission. We employ people who can calculate exactly how, and using what diameter of duct, you can stay within the limits of the noise and air velocity standards."

Air is now one of the most important elements of the building services sector in the Netherlands. And during those 40 years, Interduct has grown from a ventilation specialist for housing estate construction projects into a business group with a single source approach, including a parts company, service company and renovation company. "We can help you out with everything relating to air," Jan concludes.