Windows and doors are an extremely important aspect of energy efficiency and windows and doors are an extremely important aspect of energy efficiency and Passive House design. Much more important than I initially realized in working with the Passive House concept.
Specifically speaking, the energy efficiency performance of the windows is really the weakest point in the thermal envelope for any building. And that’s why it’s so important that any gains that can be made possible through higher efficiency can be captured. But this also needs to be a cost effective solution as the cost of the project has to be kept in mind.
In our home build, I actually put the house on hold to do a deep dive on windows and doors to find the right thing for the project. And in my mind the right thing is not only for this house but also to be able to help future projects categorize and understand the range of suppliers that have windows that meet passive house requirements, and how they all compare from a cost perspective.
I looked at a total of 15 different manufactures, with most of them were made in the US, a few from Canada, and a couple of European made windows. Who knew the Poland would produce and market windows for the US!
When it comes to windows there are basically a few types of materials and a range of other choices. There are windows made of vinyl, PVC reinforced with fiber or steel, fiberglass, aluminum clad and wood. So choosing a material is an important consideration.
Next you have to consider the style of window that you want. There are stationary windows that don’t open, but for the windows that open you have a choice of single hung, double hung, casement, awning, and European-style tilt and turn. Whew! That is a lot of choices!
For Passive House, single and double hung windows do not have the efficiency needed, and are can not be considered. Windows that can be sealed by applying slight pressure in the closing process, have the best efficiency. You also need to consider how you want the windows to open - do you want the windows to open inward or outward?
One of the manufacturers that I’ve dealt with does not produce awning or casement windows, and their reasoning was that they can’t find the quality hardware that meets their standard. And in general, after my research, I agree with them. So for this build we are going with European tilt and turn hardware that will tilt inwards, and also open to the inside. One of the reasons we chose that style of window is that we normally would not throw open all the windows in our climate. So I’m not worried about having clearance on those windows to be able to open them, and the tilt feature is a great way to let air in, but still have security.
Of the 15 manufacturers that I looked at there was an amazing difference in price with windows that met the qualifications. About five of the manufacturers do not produce the tilt and turn style, so they were immediately moved to the “not under consideration” category. Of the 10 remaining vendors, the price range was from around $60,000-$270,000!! All for the same window package! I was completely floored by this drastic price differential.
In fairness, it was not a complete apples to apples. We did not consider low-cost vinyl windows from any manufacture, and generally speaking we are looking at at least a mid to upper grade window to hit the minimum thermal efficiency as needed.
But even when it was apples to apples comparison, the difference in price was double when comparing one manufacturer to another. I normally use price as a secondary consideration and look at the value presented as the main consideration. But comparing prices is a key consideration to try and keep a project on budget and having done so I know this will help keep future projects in line with budgets as well as the quality needed in a Passive House build.
The vendor that I was thinking was the likely choice for this project also happened to be the lowest price, and this made me nervous. So I contacted the manufacture and asked where could I go see these windows in person. Sometimes touching and feeling a product is the best intelligence you can get. So it was road trip time and traveled from my home in North Carolina to Tennessee to a job site under construction to see the windows that were essentially the same window that I would be putting in to this build.
I’m glad I did that, because from a quality perspective, these windows were impressive. I got a chance to walk through a live jobsite with the windows, look at how they were to be installed, and talk to the general contractor about his experience with this company. It might seem a little extreme to travel two days to go look at some windows, but it is such an important and critical aspect of the house, that I really needed to make sure that these windows were as good in person as they seem to be on paper.
Stay tune for more details. I recognize that this build is a slower process than what it might normally be, but I need to take all of these steps carefully, so that way I’ve laid good groundwork for the future houses and commercial project. Windows and doors are much more important than you might think for a Passive House project.