Passive House Windows: Your Complete Guide
There is nothing quite like waking up to the natural sunlight softly illuminating your bedroom. As you make your way to the kitchen, a large, south-facing window allows you to watch the hummingbirds buzzing about your pollinator-friendly garden. The sun illuminates your home throughout the daylight hours, making it unnecessary to turn on any artificial light throughout the day. Large windows that allow natural light to illuminate the house cut back on the energy used for lighting and play an essential role in our mental health. One study found that hospital patients who were placed in recovery rooms with windows that offered a view of nature could recover faster from surgery with less need for painkiller medications than those who did not have access to natural light. Dozens of studies confirm that biophilic architectural design in both homes and office settings can reduce stress, improve brain function, and enhance mood and creativity.
So why doesn't every homeowner add a couple of windows to brighten and enliven their home? Unfortunately, older window technology was one of the primary sources of unwanted heat loss and heat gain. The United States Department of Energy (DOE) finds that "heat gain and heat loss through windows are responsible for 25%–30% of residential heating and cooling energy use." Though that large bay window in the living room might offer a beautiful view and biophilic benefits, it might also be driving up your monthly energy bill.
Luckily, advanced window technology has drastically improved the energy efficiency of the windows in our home. Here at Rise, we have written in-depth guides about many types of windows: from ENERGY STAR windows and the pros and cons of triple-pane windows to our comprehensive window guide and window style-specific articles like this one on casement windows. In this follow-up article, we will take a look at passive house windows and offer our suggestions for these exceptionally energy-efficient and insulating window options.
What Are Passive House Windows?
If you head to your local hardware or home improvement store and ask for the best "passive house windows," the chances are that the store employees will most likely not be able to assist you. In reality, there is no such thing as a passive house window type. Instead, passive house windows are built to a specific energy efficiency performance standard. The Passive House Standard is a performance-based standard. It is widely considered to be the world's leading standard in energy-efficient home construction.
According to the International Passive House Association website, the standard is designed to ensure homes that offer maximum quality, comfort, and energy efficiency. The end goal is for the structure to require a minimum amount of energy to achieve a comfortable, year-round temperature, making obsolete conventional heating and air conditioning systems.
Even though passive house windows don't have specifications of required components or elements, they generally have the following characteristics:
- Thermally broken: This refers to a specific manufacturing technique wherein the window frame (most often constructed from aluminum) contains a barrier between the inside and outside frames. This energy efficiency technique helps to limit the conductive thermal energy loss from the window.
- Extremely Airtight: Windows and their frames also contribute to unwanted heat loss and heat gain via gaps and fissures that lead to drafts. Passive house windows will have a strong focus on airtightness as a tight building envelope is a core principle of the passive house standard.
- Triple Glazed Windows: Passive house windows will also opt for the most energy-efficient window technology available. In today's market, triple-glazed windows with the gaps between the individual glass panes filled with argon or krypton gas are widely thought to be the most efficient option.
- Low-E Glass: Low-emissivity (low-E) glass is the industry standard. This type of glass has a thin coating of metal oxide on one internal glass surface. The metal oxide coating improves the window's thermal performance by reflecting heat into the home while not affecting the incoming external light. Windows with low-E glass allow homeowners to enjoy the warmth and light of the sun in the winter without losing interior heat.
- U-Value and R-Value Measurements: A window's energy efficiency is measured by its U-Value and R-value. A U-value is a precise calculation of the conduction properties of the different elements that make up the window. The U-Value of a window will measure the insulating ability of the window and act as an indicator of heat transfer. The R-value of a window, in contrast, measures the amount of heat retained by the window. Passive house windows will have a low U-value and high R-value. They will also be designed to maximize solar gain and minimize heat loss.
How Much Energy Do Passive Windows Save?
Upgrading to passive house windows will undoubtedly cut back on your energy use. However, the exact amount of savings will depend on the type of window they are replacing. According to one estimate, high-efficiency triple pane windows might improve up to 20-30 percent on energy efficiency. Suppose you are replacing older, single-pane windows or windows with significant and noticeable air leaks around the frame. In that case, the energy savings will most likely be even more considerable.
How Long Do Passive House Windows Last?
The most appreciated benefit of passive house windows is their ability to improve energy efficiency and lower monthly energy bills. Due to their meticulous construction, passive house windows are also highly durable. The thick, triple glazing of passive house windows offers increased durability and less threat for broken glass. The vinyl, aluminum, or fiberglass frames are also highly durable and less likely to warp or damage with time than wood. A passive house window should last at least 20 years when properly installed, but it could last for up to 40 years if well maintained.
How To Install Passive House Windows?
Proper installation is critical for passive house windows to achieve their maximum airtightness and insulation ability. For this reason, most homeowners opt for professional installation. Suppose you are interested in self-installing your passive house windows. In that case, you will need to focus on the customized measurements of the window and the frame to ensure proper fitting. All gaps and spaces also need to be filled with high-efficiency foam insulation. Check out this tutorial for appropriate installation techniques.
What Are The Best Brands of Passive House Windows?
There are dozens of different companies and brands selling high-efficiency windows incorporating the Passive House Standard's characteristics. We recommend the following brands:
Neuffer Windows
This German company specializes in making passive house windows. They have several different frame types, including aluminum-clad wood, aluminum-clad vinyl, and pure vinyl frames. The company's Eco Idealu window combines wood and aluminum and adds a layer of insulating foam. The triple glazing and warm edge spacers allow the Eco Idealu to achieve impressive passive house U-values of 0.14. They can do this thanks to their unique polyurethane insulating wedge, ensuring the aluminum does not contact the wood.
Alpen Windows
Alpen High Performance Products: This company is one of the few manufacturers offering "quad-pain" window glazing to achieve an R-value of 10. This rating is three times that of the required ENERGY STAR standard. The four panes of glass also block out 99.5 percent of UV rays, almost eliminate issues with condensation, and contribute to LEED points by improving the home's overall efficiency.
Marvin Windows
Marvin Windows also offers several high-performance windows that meet the Passive House Standards. The frames for their windows are made from Ultrex®, which is exceptionally resistant to the elements, essentially eliminating the threat of air leaks around the frame.
What Are The Benefits and Drawbacks of Passive House Windows?
Windows constructed to the rigorous and exacting Passive House Standard will incorporate a highly thermally insulating glazing, a highly thermally insulating frame, and a thermally optimized edge compound. When professionally installed, these window options will allow homeowners to enjoy all of the benefits of natural illumination, passive solar heating, and biophilic architectural design without compromising energy efficiency and thermal performance.
On the downside, passive house windows will represent a significantly higher upfront investment. For example, you can expect triple-pane windows to cost between 10 and 15 percent more than double-pane options. When combined with an airtight building envelope, high-efficiency insulation, and other aspects of the Passive House Standard, homeowners can expect a significant decrease in energy costs. These savings will result in quicker payback periods.
Article by:
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.