It is only in recent years that the importance of sealed ventilation systems has been taken seriously, at least in countries south of Scandinavia. Just a few years ago, typical duct leakage in commercial properties in Belgium was about 40%, a fact that has been highlighted by BBRI, a well-reputed Belgian test institute within structural engineering. “We have long been aware of the importance of airtight ventilation ducts and the opportunities they provide to reduce running costs and environmental impact,” says Dirk Van den Branden, Lindab Belgium. “We therefore developed the Calc-Leak web tool in collaboration with Ingenium, a renowed energy consultant, to quickly and simply demonstrate the positive effects of investments in more tightly sealed ductwork systems.”
In connection with a large rebuilding project in the city of Zwevegem, the P&P Sileghem architect’s office was one of a number of companies engaged to design the conversion of a former industrial building into a modern, energy-efficient civic centre for the city. ”Calculations showed a 20% cost saving through retaining the original concrete frame,” says Pol Sileghem, architect at P&P Sileghem. “However, it transpired that this solution would place major demands on the airtightness of the duct system in achieving the highly ambitious E42 (Low Energy Building) energy class. Through Lindab we, and the technical consultant BURO II & ARCHI+I, had the opportunity to use the then newly developed web tool, Calc-Leak. It gave us, and not least the developer, a very clear picture of savings and payback-times for the upgrades to ducts from lower tightness classes (A) to higher ones (B and C).”
“Using Calc-Leak gives us a quick overview of the savings that, for example, a transition from tightness class B to C delivers, and at an early
stage of the project,” says Dieter Lein at BURO II & ARCHI+I. “Based on these calculations we can then present different cost saving options to the developer. In the Zwevegem case it involved annual cost savings in the order of 25%. It also turned out to be necessary in order to achieve
the energy class of E42 that was set.” Calculations in Calc-Leak can be performed with both very basic data and more detailed data. Building type and floor area the most common starting points for a basic calculation of savings, with supplementary data subsequently fed in for more accurate calculations when the project plan is more complete.
“As Calc-Leak is also able to map out the financial effects of substandard airtight sealing of a duct system, it is simple to present not only the actual energy saving but also the payback time for the installation as a whole,” Dieter Lein explains further. “As in all typical projects it is very short, shorter than often thought. For example, the Zwevegem project selected a Lindab Safe Click in tightness class C. True, it entailed a somewhat higher investment cost, but Calc-Leak indicated that it would pay for itself in six months and subsequently deliver annual energy savings of around 25% compared with a more ‘traditional’ badly sealed duct system. With such interesting facts in black and white, since then we always have Calc-Leak in our tool box for showing energy efficiencies.”