Interview: Aleš Dolenc, director of M Sora
What is required for good energy insulation of a house?
An energy efficient house is linked with good thermal insulation consisting of walls, windows and doors in addition to quality contact between construction joints. Also vital is the correct installation of fittings as inappropriate or sloppy installation of windows and doors can cause great heat loss.
What is the role of energy efficient windows regarding the general energy consumption of a house?
The majority of heat loss is still due to windows, so installation of low energy windows bears even greater importance for good insulation. End-users notice the difference between classic windows with a heat transfer coefficient of 1.3 W/m2K and low-energy windows with 0.66 W/m2K saving approximately EUR 500 per year for heating. The experiences of our customers who have replaced 20 year old windows without thermopane glass panes shows that energy savings can exceed 50%.
What are the main advantages of wooden windows in comparison to PVC?
The main benefit of wooden windows is definitely their ecological aspect which automatically leads to a reduced carbon footprint. There is also the aesthetic aspect as wooden windows are considered to be part of the furniture. It is true that wood is more sensitive to moisture, hence installation timing is very important, although PVC windows are extremely prone to expansion during temperature swings. The life span of wooden windows can be greatly prolonged with proper maintenance and when also using aluminium external protection, the windows can last for a very long time. Plastic is subject to deformation due to weather and then the only solution is to replace the window as plastic cannot be maintained.
How does your company respond to the trends of energy efficiency?
Energy efficiency is no longer a trend but rather increasingly a demand which will be legalised in the next few years in order to meet the EU criteria for zero-energy buildings. Feedback from users is so good that zero-energy window development is basically the only possible way. Nearly all our windows can be regarded as low-energy (Uw<1.0W/m2K). Development is now more about their modification in the sense of even greater energy efficiency and the use of more and more ecological and renewable materials.
What are your newest energy efficient products?
Everything we make comes from our innovative ECO-S wooden insulation. The product has been a great success and has already won an award; now it serves as our guide for further development. Since the first prototype in 2009, we have already made eight variations of the windows with such coating. Five of these are a huge success in Slovenia and abroad. Many adjustments had to be made for different window models, shapes and sizes. We have individual window types where we can use wooden insulation for the entire range of windows, doors, slide windows etc. We've been further developing this concept to meet passive standards. In March we received a certificate for the passive window for two window types - M SORA NATURA E112 and M SORA UDOBJE E112 which attracted a lot of attention from experts and customers at the International Passive House Conference in May.
Are you currently working on any new projects?
Just this year we've created five new window prototypes with ECO-S coating and new products are in progress. Together with our Austrian partner, we are developing an ECO-S insulation system which we could offer to other wooden window manufacturers.
What are your development plans for the future?
Our plans for the future are clear - to continue the development of ECO-S windows. Moreover, there is increased demand for large glass elements which comprise entire facade systems so we are also already active in this field. Also very interesting is window ventilation near or on the window and we are persistently looking for solutions we can offer our customers as soon as possible.