WINDOWS ON THE WORLD – how we chose the windows for our house

Apologies for not updating this for a while but it felt a bit indulgent and insensitive to be writing about material activities connected with our build when the world is struggling with the greatest challenge in our lifetimes. I did think about sharing my thoughts on the Coronavirus pandemic in this blog, but felt that they would be just further noise and I have nothing to add to the list of issues, both positive and negative, that fill every communication channel known to us.

However given the restricted lives we are living now and the increased time at home I have decided to start writing the blog once more and over the next week or so will try to bring it up to date with what has been happening. If you are reading this hopefully you will find some distraction for a few minutes and we appreciate your continuing interest in our project.

Today I am focusing on how we decided which windows to put in our house.

Windows are central to any house design and we have all seen images of floor to ceiling glass walls of windows which make the house appear to be part of the exterior. Lovely – yes; expensive – prohibitively so; and appropriate – not for our objective of trying to achieve a passive house level of insulation.

Early in the design phase Tony our designer firmly disabused me of any likelihood that we could have vast arrays of endless glass in the living areas. We had to find a balance between openness, cost and heat loss. We visited a number of window manufacturers and eventually settled on the IDEALCOMBI FUTURA +i range. https://idealcombi.com/commercial/products/futura-plus-i/. The quality, workmanship and value for money is exceptional. The windows are triple glazed and passive House certified.

Some people have asked me about the difference between triple and double glazing and whether triple glazing is worth the additional cost. For our objective of trying to achieve Passive House standards in terms of insulation and performance triple glazing was essential. Particularly given that we have put in some fairly large windows throughout the house. A good triple glazed window can give you energy efficiencies of between 0.8 to 0.6 compared to 2.8 for double glazing – what this means in reality is a 2 degrees difference near to windows – or 18 degrees for triple glazed compared to 16 degrees for double glazed.

The science


Our windows also come with warm edge spacers which minimise energy loss. In the past standard glazed units were constructed with an aluminium spacer to hold the glass apart. However, aluminium is highly conductive and also has an exceptionally high thermal energy loss. Triple glazed windows fitted with warm edge spacer have a warmer internal edge temperature by up to 65% which helps to improve the thermal efficiency of the window and reduce the risk of condensation. Warm edge also significantly lowers the temperature differential between centre and edge of unit and up to 94% reduced heat loss (or heat gain) at the external edge of the window

A cross section of our actual windows showing the warm edge space bar


This does not mean however that triple glazed windows are right for every project. They are more expensive, they are bulkier and weigh more than double glazed units so increase installation costs. They also reduce thermal gain (though some manufacturers can compensate for this with glazing solutions) which can be an issue in the winter. So I would not say every house should have them, but for highly insulated homes, using Mechanical Heat Recovery Ventilation systems and renewable heating sources they will be the window of choice.

This shows the depth of every window!


They are however one of the single largest outlays of expenditure for any major building project. So we were on tenterhooks the day they were delivered to site. Under strict instructions from Phil Higgs https://www.hmconstructionuk.co.uk to stay away the day they arrived we waited for confirmation that they had successfully made the trip by lorry from Denmark where they are manufactured to Dorset. We were delighted therefore to receive photographs of the vehicle having arrived and confirmation that all the windows were delivered and unloaded without damage.

Windows Arriving
Unloading

Within a matter of days the windows were installed in the house, a challenging and skilful exercise undertaken brilliantly by Phil and the team, particularly given the size of some of the windows.

First one in place


The effect of installing them was transformational. Not only did they make the building secure and watertight, we also began to get a real sense of how these “eyes on our world” will frame the different vistas from our house over the years to come. So we and guests will wake up to views over the surrounding hills, we will lie in the bath and gaze at the trees beyond, and of course we have a “Loo with a view” but not so revealing as it was here before!!

4 comments

  1. Wow, didn’t realise windows could be so scientific… it’s all looking so alive now (is that a thing?) Were sorry not to have been able to get down to see you the other weekend, hopefully when things are easing we’ll visit and see this amazing project. Keep sane and safe, Di.

    • Di so sorry not to have seen you either – seems like it will be many months before we will so you too stay safe and well and look forward to catching up later this year. Xx

  2. Hi Sue, congrats on such a major project, you are leading the way to a new type of living. Well done. Weird times, good to have a dream building plan on the go.
    Much love urs & crox

    • Thanks both – sorry to have missed you the other week, hopefully we can meet before the year is out… hoping meanwhile that our project can inspire others to thinking about sustainable building. Xx

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