Glazing, Shading, Building Orientation Keep Summers Cool and Winters Warm

This brilliant video (please refresh the page if you can’t watch the video) by Trade Secrets gives you in-depth knowledge of how shading, glazing and sunlight work together to make your house cool in the summer and warm in the winter. These simple, and energy-efficient tricks work with mother nature to save you much money on your utilities.

Video and picture credits to Trade Secrets

The changing positions of the sun in different times of the day and the year have a huge impact on the solar gain/loss of our house. So what should we do to make the most of the changing positions of the sun? Lets look at glazing, shading and building layout. By following general rules when designing the building, we can capture this free energy during the winter when we need it, and block it out during the summer when we don’t.

The position of the sun varies throughout the seasons. During the summer the sun is high in the sky, and almost directly overhead during midday, and at a low angle in the east and the west in the mornings and afternoons.

Glazing

(picture credit: Suburban Windows & Siding)

Normal glass allows 90% of the sun head directly into the house. As a result, the location, size and type of the glass are critical aspects of the design. Usualy, there are more glazing on the north side to let in more winter sun, and less on the east and west to block out the heat of morning and afternoon sunlight. In short, here is the general rule for glazing: more on north, less on east and west.

The Solar heat gain coefficient (SHGC) is a measure of the  amount of solar heat that pass through the glass. The higher the coefficient glass the more heat. Glass with higher SHGC are usually installed on the north side of the building to allow the winter sun in. In the summer, it is the glazing on the east and the west that are exposed to the sun. Therefore, if possible, use lower SHGC window to keep the solar heat out on the east and west sides. Check the label to help select the right glazing. It contains SHGC at the bottom of the label.

 Shading

On the east and west external shading will be even more effective than glazing. The eaves don’t really block sun light from lower angles, so shading must be vertical such as shutters, awning blind, and vegetation.

on east and west sides:

On the north side, horizontal shadings such as eaves will sufficiently block direct summer sunlight while allowing the lower angle winter sunlight to get in. As a rule of thumb, horizontal shading should extend out about half window height.

on the north side:

Adjustable shading is also a good option, allowing occupants to control slar heat gain depending on the time and season.Vegetation is also a good choice of natural shading.

The sun also heats up roof and walls. Shading on the east and west side using vegetation can be very effective in keeping the house cool in ther summer. Colors of the walls and roofs affect how much of the solar heat that is reflected or absorbed. So in cold climates, choose darker colors to absorb solar heat, and choose warmer colors to reflect solar heat in warmer climates.

Building layout

The building’s shape and orientation will have a big impact on its comfort. Here are some tips: North-facing areas are good spots for living areas. Locating the garage and laundry on the western side will create a heat barrier to the rest of the house in hot summers afternoons. A longer northern layout allows more solar heat gaining in the winter.

If the block has a narrow northern aspect, other solutions exist. For example, splitting the house into two sections provides every room with north-facing glazing.

In sum, allow sunshine through glazing in winter, shade glazing in summer, and plan the building layout with a northern aspect.