Installing doors & windows for the best performance in high efficiency homes, LEED & Passive House

Why Installing Windows & Doors Correctly is so Important

Window & Door openings are breaches in a building envelope that need to be carefully managedin order toprevent moisture damage and air leakage in homesas well as to save energy. Water leaks from around windows and doors are the visible result of a poor fitting or sealing job, but that's far from where it ends. If there are air leaks from around windows and doors, not only is a home inefficient - ie. It's losing energy - but it's susceptible to condensation forming around these areas creating moisture that can be hidden within the wall framing or insulation and causing problems later.

Moisture & more specifically humidity is the number one cause of degredation in North American homes, because as timber is a hygroscopic material, once thelumber in a typical house wallreaches a humidity level greater than 15% the chances of insect or mold attack increase significantly. This should be kept in mind when installing windows & doors in stud walls and it's a little more complicated than sticking on flashing or basic tape, liberally applying the silicone sealant or squirting in the ubiquitous can of "not so" Great Stuff to make a connection that is neither airtight or healthy - with the foam residue and waste chemicals produced left to bioaccumulate too.

When installing windows and doors in a home, it's essential to put comprehensive strategies in place to manage moisture in all forms, being air leakage,condensation on windows which can be hard to stop, wind-driven rain & snow, as well as a straight-forward downpour, in addition to being as Eco-Friendly as possible in the process.

Preventing Water Leaks from Windows & Doors

One thing is certain, water only runs downhill - unless that is it has a reason to do otherwise.当安装门窗时，第一个基本原则是“像水一样思考”——确保所有的开口都有闪动，并用胶带妥善地贴好，并进行编码，这样想要流下来的水就可以这样做，而不是堆积起来，并且它会被引导到墙的外部。根据当地的气候条件，你必须密封洞口，以允许毛细管作用结合风压或密封风吹雪。我们通常发现，如果一个住宅结构是全面空气密封的，那么它通常也是水密封的。For the best tips on water sealing windows and doors see below, and be sure to watch the EcoHome"How to Seal Windows & Doors correctly" video Guideat the bottom of the page.

Stopping Air Leakage around Doors & Windows

High Efficiency buildings like LEED certified, Passive House, ZNE, Passive Solar, Zero Energy Homes or even Positive Energy Homes all rely on the building envelope having a high level of insulation, and a managed level of Air Transfer Rate, preferablyvia an HRV or ERV unit to control the energy losses from essential ventilation．You can read more aboutAir Permeability of homes here, but to put it simply let's quote from the US Department of Energy when they state "the average home has the equivalent of a 2ft square hole in it．" The next time someone in your home complains of feeling a draught or if your utility bill is burning a hole in your pocket, if your doors and windows weren't properly sealed, remember that 2ft²hole in your outside wall!

We're not helped in North America either because most homes are stick-built and as wood is a living material it does move with changes in the weather and over time. Succesfully sealing windows against air-leaks relies on flexible seals being fitted between the frames and the framing, often calledAir Sealing System Tapes，这是一个有效的外部绝缘和饰面系统(EIFS)的一部分。我们还应该记住，门和窗如果装得不紧，它们本身就会动，但这并不一定意味着要关得紧。一定程度的灵活性是必不可少的，市场上的许多产品也有助于水封——有效地一举三得——但就像大多数建筑材料一样，重要的是在正确的应用中使用正确的产品。更具体地说，当你在安装高性能门窗的时候，你真的需要预算足够的蒸汽开启，外部空气密封羊毛背胶带与全表面粘合剂的平衡。请参阅下面的小贴士和视频了解具体细节，并考虑作为免费会员订阅EcoHome，因为我们经常提供环保EIFS产品的会员专属优惠。

How to Install Windows & Doors Correctly

The following window and door installation tips will improve any building structure, whether a new home build, or a DIY home renovation. All the same, asEcoHome is all about LEED, Passive House, ZNE, Passive Solar or Zero Energy Green Home Construction, we can say definitively thatthe tips below become even more pertinent the higher-performance the home is designed to be - and especially important if using the latest generationsuspended-film insulating-glass glazing units and windows．

1. Angled bottom sills:通过在轻微的角度上建造你的窗台，任何水找到它的方式将被引导到外部。
2. Window flashings:after wrapping weather barriers into place and taping them down, install window flashings that will safely direct any incidental water safely onto your weather barrier/drainage plane.
3. Don't attach windows by putting screws through the shims.Put the screw either just above or below, then remove the shims when the window is secured. Shims will offer little insulation value, and are most likely wet when purchased and installed, so as they dry they will shrink and allow air to leak out and in.
4. Block supports:windows will often come with wooden support blocks on the bottom, or they are usually added in the form of shims or small blocks of plywood or OSB sheathing. They are necessary to allow a bottom space for insulation. But they are only necessary during installation - once windows are screwed in place, they are supported and the blocks can be removed. If you are using spray foam do either side of the blocks, and when it sets remove the blocks and insulate in those empty spaces. Wooden blocks will create athermal bridge在你的窗户下面，一个冷点会产生冷凝。你也可以用泡沫塑料或者坚硬的矿物棉来代替木块，这样就完全解决了这个问题。We have found usingmineral wool insulation(Roxul Comfortboard) makes leveling and placing windows quite easy. It is somewhat compressible and it holds its R value when compressed, and it isn't harmed by moisture the way fiberglass insulation can be.
5. Create a durable air seal:low-expanding spray foam is commonly used around windows, which works fine for its insulation value but it is not flexible enough to withstand the normal shifting and still provide an air seal. Adding a bead of acoustic seal, caulking or taping window frames to rough openings can be a quick and easy step that will further reduce any risk of air leakage between window frames and rough openings.
6. Inset windows:position windows towards the center of the rough opening rather than installing them flush to the outside. Windows that are installed at the exterior point of openings have a lot more thermal bridging around the frames. Windows in the centre of the opening reduce the risk of condensation by keeping window perimeters warmer. The added benefit that isn't always considered is comfort. Thermal bridging and poor quality windows can make it quite unpleasant to be near exterior walls on the really cold days.
7. Use High Performance insulating window bucksinstead of regular window bucks made of ordinary lumber - especially when the wall assembly includes a continuous external rigid insulation layer.

How window placement effects thermal bridging

Thermal bridging around windows and doors results in loss of energy, cold spots, condensation points and potential wall damage. To demonstrate the importance of window and door placement relative to the wall's exterior, we ran some thermal transmission tests with the following results.

Images like the following can often be hard to read without knowing what you're looking for, but the short story is this - when coloured lines are closer together the heat flow is more dramatic.

颜色较粗的线表示热量通过它所花的时间较长。或者通俗地说，在寒冷的气候条件下，这意味着你的房子里有更多的热量，你的口袋里有更多的钱，或者在温暖的气候条件下，室外有更多多余的热量，空调的负荷更低，也可以省钱。

The images below simulate an exterior temperature of 0 °C and an interior temperature of 20 °C, with a triple pane window. In the first diagram the window is installed flush to the exterior of the insulated wall, with a heat flow of 7.9W. The second diagram indicates the same conditions but with the window inset into the rough opening, leading to a heat flow of 7.6W.

Thermal bridging through flush mounted window frame © Denis Boyer for Ecohome

Thermal bridging through inset mounted window frame © Denis Boyer for Ecohome

The above simulation is of just one part of one window, and with an assumed heat differential between inside and out of only 20 degrees Celsius.

What this means in real terms: multiply that amount of heat loss to match the average house size with the average amount of windows over the average North American or Canadian winter and you could be looking at something like an additional $20-$30 on your heating bill, not because of the windows you purchased but simply because of where you placed them.

So for fun, keep multiplying - if you can find 10 more places in your design where a slight modification can eliminate a seemingly insignificant thermal bridge, you just trimmed hundreds off of your annual heating bill. Unchecked thermal bridging in a building envelope is like death by a thousand cuts. One won't kill you but they start to add up.

And if youreallywant to split hairs, having your window inset by no more than 1/3 will offer you that reduction in thermal bridging but maximize interior passive heat gain, which is slightly reduced the further to the inside that you place your window.

Correct Choice & Fitment of Doors & Windows makes a measurable difference

Windows can really make or break the comfort and efficiency of your home．选择正确的窗户并安装它们以获得最大的性能和耐用性(在寒冷的气候下尽可能多地安装南侧，在温暖的气候下尽可能多地安装北侧)可以使您的家庭生活明显更愉快，节省您的钱，并保持墙体结构在更好的条件下，更长时间。To discover how to choose the best windows for your house, see hereorsee here to know which type of window frame to choose between wood, aluminum or PVC / Vinyl

Top Tips: For Well Fitted & Sealed Windows & Why It's Important:

• Attention to Detailis essential when fitting windows and doors - for all the reasons above
• Use the Right Specialist Materialsas using the best materials available ensures good sealing that lasts
• If we were talking about sealing a Boatwe wouldn't have to stress the point, trust us, without properly installed and sealed windows and doors, your home's performance is also sunk!

Further reading for water & air sealing & building envelope permeability in homes:

• Find outAll about Air & Vapour Barriers in High Performance Homes- EcoHome Guide
• Discover the Aerobarrier Home & Attic Air Sealing Spray- EcoHome Guide
• Replacing Polyethylene Vapor Barriers with Paint- EcoHome Guide