by Skander Spies
Serious cold temperatures, like the ones hitting most of the country right now, have a habit of making buildings “speak up” to their owners about a range of insulation, air sealing, and heating issues. Every winter we get a number of calls from owners with two particular issues: they have ice building up on the inside of their windows, ice on their walls, and/or they have water dripping out of their recessed can lights (or damaging the drywall around the light fixture). This post talks about why you get window condensation and ice can form on the inside of your windows. Our next post will talk about why recessed can lights can cause moisture damage or start to drip water inside your building.
Many people have seen condensation and ice form on the inside panes of their windows. While it is most common on single pane windows, it is still a common problem for double pane windows in cold climates. This problem is related to something called dew point which describes the temperature at which window condensation occurs due to the moisture content of the interior air. There are several factors that affect the dew point temperature, and when you will get condensation.
Low thermal performance - most windows, even double panes, simply let lots of heat out. My mother refuses to sit near the windows at restaurants in the winter, because they make her feel cold. In the winter, the temperature on the interior surface of the window drops, because the window doesn’t insulate against the cold outside air. How far does it drop? With a modern double pane window (usually about R-3, learn more about R-value here), if the outside temperature is 0F and the inside temperature is 70F, the inside of the window pane will usually be about 44F. Yes, that’s 44F inside your house, and is the dew point if your house is at 40% humidity (which is a typical “comfortable” level). The interior surface temperature will continue to drop with the outside temperature, making condensation more likely, even at lower humidity levels. To keep your windows condensation free in almost any climate, you’ll need a window with a thermal performance of R-5 or better.
Humidity - if you have a larger family, pets, or cook a lot, then you are generating quite a bit of moisture inside your house. As you add moisture to the interior environment, it becomes easier for moisture to condense on the cold surfaces we described above. The colder the surface, the more condensation you get. If the surface is cold enough, the condensing moisture will freeze and turn to ice. Keeping your interior humidity below 30% is a good target to start with, but is not guaranteed to stop all window condensation. A heat recovery ventilator is one way to control this humidity level by removing excess indoor humidity (it also removes pollutants like pet hair and dirt, learn more here).
Air leakage - windows are a critical part of the “air barrier” of your building, meaning that they seal outside air away from the inside air (that you want to keep warm). If your windows are not installed properly, they will leak air, even if they do not open. Operable windows (like a crank open or slide open model), tend to leak even more air, especially as they age. Cold air leaking through the window opening or around the sash (the part of the window that moves) will further reduce the interior surface temperature, making it more likely to get condensation and ice on the inside of the window. Casement and awning (or hopper) style windows tend to provide better airsealing performance, while horizontal sliders, single hung, and double hung windows can leak severely.
This site has a quick calculator that shows the relationship between air temperature, humidity, and dew point temperature (the surface temperature that the interior glass needs to be above to avoid condensation).
This site has several charts that outline what conditions are likely to create condensation on windows.
Getting ice on the interior of your window means that the interior surface temperature on the inside of the window is below 32F- bad news for your energy bill, but really bad news for being comfortable in your home. Window condensation or ice inside your windows can cause several problems:
- Long term damage to the window unit: Moisture (either as ice or water) will cause wood windows to swell and shrink, warping the frames and occasionally calling glass to crack. This also increases air leakage problems.
- Health issues: moisture from window condensation and ice can become a petri dish for mold and other lung & sinus irritants.
- Comfort: condensation and cold surface temperatures are unpleasant to be around. What good is having a beautiful picture window if its it too uncomfortable to sit around? Your quality of life goes down when you cannot enjoy your home or office completely.
- Energy costs: if your windows are cold and leaky, chances are you’ll be raising the thermostat to try to compensate for the problem, which is expensive and frustrating. Most heat distribution systems do target delivering heat near windows, but extreme temperatures will usually win out, leaving you with a big energy bill AND an uncomfortable home.
Contact Energetechs to learn more about how window replacement, heating improvements, and ventilation systems might be able to alleviate your window woes. Until then, stay tuned for our next installment on recessed can lights!
At Energetechs, our mission is to create buildings that enrich our environment, our community, and our quality of life. This season, we are exceedingly thankful to prove this mission on every working day.
We are thankful for our clients that share this mission.
We are thankful to be part of a community of people and organizations that also pursue this mission.
We are thankful for the people on our staff and make Energetechs a great place to work.
Thank you for reading this blog, and we wish you an abundant holiday season.
A few weeks ago we had a very important arrival in our office- two beautiful samples of the newest Zola window. Architects have long loved the elegance of a slim aluminum frame windows, and these windows have traditionally had terrible energy, air sealing, and sound performance. Called ThermoMulti3x and ThermoMultiAero, these new units bring a new level of comfort and energy performance to aluminum windows in residential and small commercial construction. This post explains why these aluminum windows are unique in the marketplace.
Clean looks are in and thicker European window frame styles have long struggled to gain market share in the United States. The ThermoMulti units are designed to fit a more modern architectural style. A few features:
- 2-15/16” overall jamb thickness
- Frames designed to allow exterior cladding to cover the frame
- Sash frames are recessed into the exterior frame
- Optional seamless welded aluminum corners
- Optional fully concealed tilt and turn hinge hardware
- Available in 16 standard exterior colors and up to 300 custom colors
The clean lines on the ThermoMulti aluminum windows are simple for designers to match and maximize the feeling of connection to the outdoors.
Energy savings is one of several aspects in which the Panoramic line offers exceptional performance. All aluminum framed and curtain wall windows typically offer a thermal performance of R-2 or R-3. They are prone to condensation (also called fogging), sound transmission, and air leakage from thermal stress. The Panoramic View windows offer superior performance in each of these categories:
- Optional soundproofing to 47dB (this reduces outside sound transmission by up to 93%)
- Three layers of airsealing gasket in every operable unit
- R-11 glazing package is standard on all units
- Whole window thermal performance of R-7.1 (ThermoMulti3x) and 8.1 (ThermoMultiAero)
- Tunable solar heat gain coefficients from 0.28 to 0.63 (0.54 is standard)
This level of performance means that designers can pursue a clean modern look without worrying about condensation, comfort issues, or sacrificing design goals like Passive House.
To complement their clean profiles, the ThermoMulti line come in a wide variety of form factors. The ThermoMulti line are available in tilt & turn and fixed windows, as well as in lift & slide, tilt & slide, French style and entry doors. They can also be mulled into multiple units to offer a high performance curtainwall style system for high performance commercial buildings. Zola has long offered expansive size options to provide maximum design flexibility, and the ThermoMulti line is no different. Fixed panes up to 8’x10’ and tilt & turn units up to 5’x5’ are common on the standard production line. Even larger sizes are available with custom engineering.
We are proud to offer a truly energy efficient all aluminum window. Schedule an appointment or email us to learn more about this unique product.
November 5, 2013
Sustainability at Oregon Institute of Technology
In addition to having one of the top engineering programs in the country, the Oregon Institute of Technology is a shining example of eco-friendly sustainability and renewable energy use. OIT introduced the very first Bachelor of Science program in Renewable Energy Systems. Their renowned Geo-Heat Center also serves as a national hub for geothermal information and development. Oregon’s elected leaders also chose OIT to be home to the Oregon Renewable Energy Center.
OIT is located within the city of Klamath Falls, Oregon. The city itself is known for its proximity to natural geothermal springs which it currently uses to provide geothermal heat to homes, schools, commercial buildings, municipal government buildings, process heat for the wastewater treatment plant, and for snowmelt systems for sidewalks and roads. Nestled in the Klamath Basin on the eastern slopes of the Cascade Mountains, Klamath Falls is surrounded by stunning natural beauty; certainly an inspiring setting for creating an environmentally-conscientious culture.
Solar Photovoltaic Panel Array
Klamath Falls calls itself, “Oregon’s City of Sunshine.” Generally, the sun shines there 300 days out of the year. OIT wants to power itself entirely using clean renewable energy. To help achieve this goal, OIT is installing a 2.0 MW solar array. The 7,800 solar panels optimally placed on nine acres of hillside will generate enough electricity to power approximately 35% of the campus. The solar array at OIT will be equivalent to 225,150 gallons of gasoline saved.
OIT claims that when used in conjunction with the soon-to-be completed 1.75 MW geothermal power plant, the campus should be able to generate most, if not all, of the electrical power it needs.
by Skander Spies
Here at Energetechs we’ve pulled up our gardens and found our hats and gloves for biking to work. Autumn sends all kinds of signals, and chances are that one of them is coming from your furnace. Thinking about winter, many of our clients start asking questions about insulation or air sealing to keep their homes warm and comfortable. While these are great questions to ask, a furnace replacement is often the most effective first step to reduce utility bills, while increasing comfort and air quality. This post is about 3 reasons why replacing your furnace is one of the most important home investments you can make.
Reason #1: Safety
We’ve all heard that heat rises. Most furnaces built and installed before the mid 1990’s relied on this fact to operate properly. These furnaces use some of the heat from burning natural gas to lift exhaust fumes up the furnace flue and out of the living space. This type of furnace is called “atmospherically combusted” and it means that your furnace is open to your living space. This also means that your furnace sucks warm air out of your house, increasing your heating bill and causing uncomfortable drafts. They also usually require “make up air”- which is a fancy name for a big duct in your house that dumps cold air from the outside directly into the furnace room. When your furnace is open to your living space, you can run the risk of “back drafting” meaning that not all the exhaust leaves the house, putting you and your family at risk of carbon monoxide poisoning and other issues. You can read more about back drafting here, and from the US Department of Energy.
Starting in the late 1990’s “sealed combustion” furnaces started becoming popular and affordable. These units have sealed pipes that keep the exhaust gas away from your living space. This single difference means your gas bill gets about 15% smaller, your house will feel less drafty, and you don’t run the risk of exhaust gas poisoning.
Reason #2: Comfort
As we discussed above, older furnace suck warm air out of buildings. This can cause uncomfortable drafts throughout your home as the furnace sucks in cold air from the outside. There are several other advantages associated with newer furnaces:
- A new furnace can be sized properly. Most older furnaces are too big for the houses they serve, meaning they turn on and off again, making noise and blowing air around. A furnace that has been sized for your home will turn on and off fewer times per day, which reduces noise and increases the lifespan of the furnace. When you talk with a contractor about replacing your furnace, insist that they perform a “load calculation” which will determine how big your furnace needs to be in order to heat your home.
- A new sealed combustion furance will have a quieter fan and (probably) multiple stages of operation- meaning your house won’t sound like a jet engine when the furnace kicks on.
- Older furnaces can be harder to maintain, and in our experience that usually means that they are maintained poorly, if at all. Having your furnace fail in the middle of January is no fun, yet many older furnaces do. If you have an older furnace, make a plan to replace it, so you aren’t grasping at straws when the snow starts to fly.
Reason #3: Air Quality
Your family deserves a better filter!