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April 17, 2012

This type of the workshops I want to attend more often!

Workshop on the Desire for Northern Living, March 5, 2012, Alta, Norway

I have attended this workshop with more than 20 professional builders, designers and architects. The topics of the workshop focused on the economical retrofitting solution from an Alaskan perspective; how far we can go in super-energy retrofits and on ventilation which keeps tight northern buildings healthy?

Two presentations focused on retrofitting solutions for buildings in the Arctic: one from an economic perspective and other view from super-energy savings. The first presentation was an interesting project from Alaska about the cost-effective (and cheap) methods for building renovation using densely-pack cellulose and installation of exhaust fans. In the house with a foot print area of 88 m2, on average 50% savings were possible with this renovation model at a total cost of $25,000. Another interesting method was a wrap-up solution for the renovation of standard wooden houses in Greenland. The theoretical model with highly developed detailed solutions for the building envelope was highly praised by the audience. Hopefully, the full-scale model would be soon built and the monitoring system would prove that this is a good and reasonable solution.

The ventilation solution in Greenland was a case-study of the local dormitory building, where the floor heating and heat recovery system are used for heating and ventilation. A few solutions proposed in the building do not work mainly due to climatic differences. For example, a trigger for defrosting of a heat exchanger unit by increasing the speed of the unit is based on the relative humidity sensor. However because the humidity levels in Greenland are generally very low, the trigger never triggers. Two heat recovery units positioned at each end of the building provide constant airflow (CAV) and run only on 10% of max power when the dormitory is unoccupied. The solution would be to have a simple variable air flow (VAV) based on a manual switch would be the cheapest solution, but naturally a demand-control ventilation system (DCV) would work best.  Surprisingly, there is no tray in a unit for dripping water below the inlet, only below the exhaust. The presentation was honest evaluation of the solutions which were designed for Denmark, but do not work in Greenland!

The most enjoyable and common sense presentation was about ventilation systems. I enjoyed the statement that a “catalogue” of efficiencies of heat exchanger units is in a world of dreams, although many people wish for it. Although the plate heat exchanger has no leakage, it freezes when it is wet and with temperature below 0°C. Rotary heat exchanger offers higher temperature efficiency and it can recover moisture but it may transfer odor probably via moisture. Typical freezing protection in heat recovery units is controlled and sensed by a detection of temperature or pressure drop. Freezing blocks part of supply flow. Freezing can be solved with the bypass of air (balance control is necessary) or preheating of air (air through heat recovery all time) or within limits speeding up the rotor. Any solution for freezing reduces the recovered heat and more complicated concepts are almost non-existing or not functioning properly (change directions, two changing recovery units).

I really enjoyed this workshop where the focus was on existing buildings as by 2050 more than 60% of buildings are already built. The professionals participating in this workshop came prepared to discuss problems and propose solutions for existing housing in the Northern regions. I strongly believe that such a workshop with the time not only to listen to interesting presentations, but to discuss it with the audience was the most beneficial workshop for all participants.