Posts Tagged ‘building envelope’

Skylights’ Function in The Active House

March 12th, 2014
Velux skylight operable with blinds

Velux skylight with blinds and operable glazing

Some green builders and energy auditors would argue that skylights have no place in a “green” home. After all, skylights puncture the building envelope allowing heat to escape in the winter and enter in the summer. Improper installation of skylights can add problems such as condensation build-up inside and ice damming outside.

However, in a house built to Active House standards, energy is an incorporated into the design but is not the driving component.  An Active House balances energy efficiency and human comfort by allowing natural daylight, fresh air and summer cross breezes into a building, while excluding excessive heat, cold, and glare from direct sunlight. This goal naturally means the home will have an abundance of windows and skylights — a direct contradiction of building philosophies such as Passive House which requires extremely tight building envelopes.

There have been many studies done on the positive effects of natural daylight on people’s health, and for those of us who live in northern climates and have suffered, even a little, from seasonal affective disorder, they will recognize the value of natural light, especially in the winter months. So while building envelopes are compromised with the addition of skylights, other green building goals are more than satisfied.

VELUX, a company established in Europe over 70 years ago, is well-known for its high-quality skylights. It has been involved with the Active House philosophy since its inception. I spoke with Nels Moxness and Russell Ibbotson of VELUX about the roles of skylights and their pros and cons in any building.

There are four major issues/concerns people have with skylights: air tightness, insulation value, solar heat gain and glare.

Air tightness: It’s no secret that many people who have lived in a house with skylights have experienced leaking at some point. While it can be due to faulty installation, often it is because the original skylights were installed using tar as the sealer around the flashing. Nels told me that after a few years of exposure to weather elements such as heat, cold, sunlight, water, snow, etc., the tar shrinks and cracks allowing water to infiltrate and find its way into the house. VELUX has always used a an engineered flashing which does not require sealants to maintain water tightness.  Their current product has the addition of  a rubber based membrane, which provides a shield from ice and water that often outlasts the roof’s shingles and prevents leaking. Further, to ensure proper installation of its skylights, VELUX certified installers  are required to attend a comprehensive installation training as well as have a job site inspected upon completion.

Insulation: With respect to insulation values, VELUX skylights are double-paned, flat glass, LoE³  that are filled with argon gas. This provides for a better insulation value than uninsulated skylights. The U-value for the installed skylights in the Active House in Thorold, Ontario is rated at 0.4 in Energy Star zones A, B and C (most of Canada’s population lives within these climate zones, Zone D, the coldest, covers the Arctic).  Note that there are 14 skylights in the Thorold house and the house achieved 1.6 air changes per hour. To give you an idea of how that compares to building code, the upgraded Ontario Building Code, 2012, and the newest Novoclimat (Quebec) building code require a minimum of 2.5 air changes per hour for a detached home.

Solar Heat Gain and Glare: Often, even in winter, if the sun is beating down on a house, without the protection trees or other buildings, the area under the skylight within the house will become so hot or bright that you avoid it completely. This effect is particularly brutal in the summer and will have the added consequence of forcing your air conditioner to work overtime. In fact, solar heat gain and direct glare from poorly placed skylights can negate any natural daylight advantage there is to installing them in the first place. Nels mentioned that with respect to solar heat gain, in the latest VELUX skylights, there is three times less solar heat gain than there was even ten years ago.  Further, VELUX is developing an exterior awning system to prevent solar heat gain and help block glare even more. As it is, you can add an interior blind system, operated by remote control, this is particularly relevant in a bedroom if you don’t like waking up with the summer sun (in Montreal in June, dawn starts around 4:30am and sunrise is at 5am). In fact the addition of a light-blocking blind to a skylight can increase energy performance by as much as 45%.

As the technology of skylights continuously improves, skylights’ importance  in a home’s design and functioning becomes increasingly valuable and homes built to Active House standards take full advantage of the newest skylights’ multi-functional qualities.

The multi-functional skylight:  The Thorold house is designed with 14 skylights which are used to bring daylight into areas that might not receive it otherwise such as bathrooms and stairwells. With increased daylight, demand for electric lighting is significantly decreased versus a standard house.

The ability of VELUX skylights to open to let in fresh air and let interior hot air escape allows architects who promote natural over mechanical ventilation to make use of stairwells as heat stacks.  When the cooler night air advances, ground floor windows can be opened along with skylights. As the hot air escapes through the skylights, the cooler night air gets sucked into the house to replace it. Cooling down a house is much more rapid, easing pressure on air conditioning and the electrical load.  Further, VELUX has just incorporated a solar panel into its skylight to operate it, so there is no need to add to the electrical load.

Rain Sensor: Because the skylights are operable, they include a rain sensor so if you aren’t home and it rains, they will close automatically.

Effectively placed and properly installed skylights can be a positive addition to any building, providing natural daylight in hard to reach spaces, lowering electrical lighting loads and improving occupants’ overall well being.

To find a Velux dealer near you visit the Velux website.

 

The Importance of an Energy Audit, Using Infrared Imaging

January 30th, 2014
Thermal energy loss

Thermal energy loss

An energy audit could be the only thing between you, a safe home, and a full wallet.

Canadian buildings, according to the Canada Green Building Council, consume up to 38 per cent of all secondary energy use, which is energy obtained from primary energy sources. Residing in your home, you consume energy in many ways: cooking dinner on the stovetop; running water for your bath; refrigerating your leftovers; and, of course, heating your home.

You might turn the lights out before bed and take care not to waste water. Though this effort certainly helps conserve energy, consider the possibility of problems in your home that are nearly impossible to detect yourself; difficult to control; and ones that are ultimately preventing you from achieving an energy-efficient home.

Finding out if your home is energy-efficient

Consuming energy is inevitable and, in fact, necessary. However, we can be smarter about the ways in which we do so and we can make our homes more energy-efficient, which in turn will ensure they are safe and sound, warm and dry, and even help patch up that hole in your wallet.

First, you need to find out how your home is using energy. Taking a look around on the inside or outside of your property, you might spot the source of a leak or draft. In many cases though, the issue is more subtle and out of sight. The only completely reliable way to find out how your home is using (or losing) energy is by having a certified and experienced inspector visit and carry out a thorough energy audit.

Infrared imaging for your energy audit

An energy audit using infrared imaging is both an accurate and completely safe way to detect whereabouts you’re losing energy. However, an infrared inspection can be complex and is most reliable when a thermal imaging expert conducts the energy audit—surveying your home’s whole envelope and indoor environment—and properly interprets the results. This way, you’ll save time and, ultimately, money.

Carrying out an energy audit via infrared imaging allows the inspector to detect several major problems, including the following:

–          All moisture buildup

–          Leaking or burst pipes

–          All areas of water intrusion from outdoors in

–          All areas where there is indoor air escaping your home

How an infrared inspector detects your home’s energy conservation

A certified infrared inspector, using a high-resolution infrared camera, is able to detect any problem that may be preventing your home from maximising energy. The camera picks up the energy flow inside the house, reading where and how it’s being used. The inspector weighs the energy input against the output and is then able to tell the energy conservation of the home.

Depending on his or her results, the inspector will inform you of the ways you can improve energy efficiency, through repairs, renovations, upgrades or other lifestyle modifications. A sustainable energy environment, or green building, can be achieved, regardless of whether you’re in the building process or you’ve been living in your home for decades.

Choosing an energy-efficient home

An energy audit may not be in your budget. However, if your home has heat escaping or isn’t making the most of its energy, you should begin to assess the pros and cons at hand. A situation like this is not only costly itself, but it can be dangerous.

Often, the problems detected during the inspection are ones that must be fixed immediately. For instance, moisture buildup jeopardizes the structural integrity of your home and can lead to black mold growth within 24 to 48 hours.

When you own a home, you’ve committed yourself—your time, money and attention—to maintaining it. Be certain its energy consumption is neither costing you a fortune nor risking your comfort and safety.

 

Article written by Ivan Ward, Inspector at  Mold Busters– Infrared  inspection services from Ottawa.

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