When “Djingis Khan” – a resi­den­tial complex in the southern Swedish city of Lund – was planned, the criteria were clear: it aimed to create living quar­ters in a pleasant atmos­phere with room for social and cultural exchanges. And things had to be done quickly, as there was a lot of demand among students. In a short space of time, the prefab­ri­cated modules resulted in 316 two-floor lodges, grouped by 20 indi­vid­u­ally designed farms. In 1981 “Djingis Khan” was trans­formed into a resi­den­tial housing asso­ci­a­tion within HSB, a coop­er­a­tive company focused on facility manage­ment. Today, many fami­lies with chil­dren live in “Djingis Khan”: living in a green space in close prox­imity to the city makes this partic­u­larly attrac­tive for them.

Jan Sörensen (left) and Anders Nilsson above the rooftops of Lund. (Photo | ebm-papst)

A good indoor climate was required

However, the require­ments for venti­lating houses have also changed in recent years. Self or joint venti­lation used to be imple­mented. The pres­sure differ­ence between the inside and outside auto­mat­i­cally ensures a certain amount of air exchange, but it was not satis­fac­tory. Aiming to improve the venti­lation and thus the climate inside the build­ings, the people in charge discussed installing a mechan­ical venti­lation system back in the 1990s.

“We wanted energy-effi­cient, quiet fans. That’s why the choice fell on EC fans from ebm-papst.”Anders Nilsson

Addi­tional insu­la­tion has also been applied and energy-saving improve­ments have been made to the crawl spaces. In 2017, HSB finally equipped ten apart­ments with systems for mechan­ical exhaust air and pres­sure-controlled venti­lation. AC fans were initially used. However, these required addi­tional noise insu­la­tion because the noise level was too high.

EC a must!

Nilsson super­vised the process over the years. He is the owner of VFS Ventser­vice in Lund and is respon­sible for plan­ning and imple­menting the venti­lation system for “Djingis Khan”.

“Dschingis Khan” was the largest order to date for Anders Nilsson, who installed all 316 fans by himself. (Photo | ebm-papst)

Nilsson recalls, “When we carried out the tests with the AC fans, the focus was exclu­sively on improving the venti­lation system. But since then, there is also greater demand for energy effi­ciency and fans that are as quiet as possible.”In a nutshell, AC fans are too loud for today’s stan­dards and consume too much elec­tricity.

Nilsson researched alter­na­tives and found what he was looking for: “When ebm-papst devel­oped its new series of sound-insu­lated roof fans with an energy-effi­cient EC motor and a temper­a­ture and pres­sure control option, the deci­sion was easy,” he says. The people in charge at HSB were also impressed by the new tech­nology and Nilsson got started with the detailed plan­ning.

Together with ebm-papst sales engi­neer Jan Sörensen, he set about selecting the compo­nents. They chose the MXRC22R roof fan model. Sörensen explains, “We develop and produce the MXRC series here in Sweden. It satis­fies all the require­ments currently being placed on roof fans: The sound insu­la­tion ensures a low noise level, and they have high effi­ciency levels and inte­grated control elec­tronics. What’s more, they are energy effi­cient.”

Light fans are used on the roofs of “Djingis Khan”. They weigh 13 kilo­grams, have an output of 85 watts and reach a free-air flow rate of 936 m3/h. The MXRC22R fans are deliv­ered with a control system with Modbus RTU. This enables a wide range of program­ming options for effec­tive and demand-based venti­lation.

Assembly made easy

Sörensen reit­er­ates, “The fans make work much easier for installers. For example, the control connec­tion is housed in a sepa­rate box on the inside of the fan housing. What’s more, the roof fans have a folding floor frame that stabi­lizes the fan during instal­la­tion.”

When it comes to resi­den­tial venti­lation, the most impor­tant thing is the noise level. The EC fans are as quiet as a whisper. (Photo | ebm-papst)

For Anders Nilsson, this is an impor­tant issue. After all, he was the one to install the 316 fans. For him as a small busi­nessman, it was a Herculean task, which he set himself alone – in close coop­er­a­tion with an elec­trical tech­ni­cian and a construc­tion company.

Nilsson smiles and recalls, “That was the biggest project ever for me. I completed the work in autumn 2021, but I started it a few years before. We decided to install 100 fans per year, and I had the option of plan­ning the work during the summer months, which of course was a major advan­tage. This is because installing roof fans in winter can be diffi­cult!” The ebm-papst fans being easy to assemble ensured smooth oper­a­tion and every­thing went as planned.

The resi­dents of the estate and the housing asso­ci­a­tion are also satis­fied with Nilsson’s work. They are partic­u­larly pleased that the fans have a low noise level and that their homes have reli­able venti­lation. Thanks to their higher effi­ciency and intel­li­gent control, the fans consume less power. They are set for a need-based venti­lation that saves energy, since they reduce the flow to the needed level. Overall, the “Djingis Kahn” resi­den­tial estate achieves energy savings of 30 percent per year compared to the previous instal­la­tion using AC fans. All those involved agree that this retrofit has paid off.

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