WINDOW ORIENTATION AND PLACEMENT- IN BUILDINGS
The positioning of the windows in your home can also make a huge difference to energy efficiency and the admittance of natural light. Correct window placement can help create a brighter, cleaner, and healthier environment in your home. Window and home design can make a huge difference in utilizing the sun as a source of home heating.
Building Orientation
Because the sun rises in the east and sets in the west, the side of the building that is utilized for solar gain needs to be facing the south to take maximum advantage of the sun’s potential energy. If the building’s axis is located on the east-west direction with its longest dimension facing the south, more of the building is situated to absorb the sun’s heat energy.
Passive solar buildings are typically rectangular with the long side of the building facing south. The distance from the source of incoming heat (south) to where it is absorbed (typically a northern wall) should be minimized. The resulting shape is a rectangle. This is one of the lessons learned in the construction of this Off Grid Passive Solar Earthship-Style Home.
South Facing Windows and Orientation
It is ideal to have the windows (solar glazing) within 5 degrees of true south. However, windows that are within 15 degrees of true south are said to function almost as well.
As the degree difference from true south expands, the overall potential solar efficiency of the structure decreases. Put another way, the greater the degree of variation from the true south, will decrease the amount of the building’s solar gain. As a result, larger amounts of supplementary energy may be needed to heat the building in the winter. As the building’s glass (glazing) faces more to the southwest, more energy may be needed for summer cooling.
Southern facing windows (southern solar glazing) are a vital component for a passive solar design and building. Because the southern side of the building is the side that will potentially receive sunlight throughout the day, most passive solar buildings will feature glass dominating the southern side. The southern facing glass allows the sun’s energy to be absorbed and distributed through the building’s thermal mass.
You may hear people referring to glass as glazing. Glazing is the fancy architectural word typically used for southern-facing glass that has the capacity to transfer the sun’s energy.
Another benefit of having windows on the south side is that it allows natural light to bathe the house throughout the day. This aspect can also lower energy use throughout the house since it minimizes the use of artificial light.
All of these factors can be used to one’s advantage, depending upon the site location and depending on the specific characteristics that you want within the house.
While southern facing windows (glazing) are a necessary component of passive solar design, care must be taken to insulate them in the winter after the sun goes down, as well as shade them in the summer.
Note that because the Earth is a sphere, depending on where you are located, the sun will interact slightly differently than in other places. For example, the angle of the summer and winter sun will be different.
If, however, you are located in the Southern Hemisphere, in order to build a passive or active solar home, the building will need to be oriented to the north.
Vertical and Angled Glass (Glazing)
The most glass that is used in buildings is vertical. Angled glass, however, is frequently used in passive solar design because it increases the amount of solar energy that can be absorbed. Caution! This can cause overheating in the summertime.
This information pertaining to facing windows to the south works for those in the northern hemisphere. Down under, in order to use solar gain, they need to face the windows to the north.
Also, a Good house and window orientation increase the energy efficiency of a home, making it more comfortable to live in and cheaper to run. The most important orientation aspect to consider is the direction your house and windows face and their solar access.
In high humid climates and hot dry climates with no winter heating requirements, orientation should aim to exclude sun year round and maximize exposure to cooling breezes. In all other climates, a combination of passive solar heating and passive cooling is required. The optimum degree of solar access and the need to capture cooling breezes will vary with climate.
It’s important to design your home for the entire year, not just one season. The ideal house orientation is one that runs along an East-West axis so that wall areas receiving hot morning and afternoon sun are minimized. Also, take into account the location of landscape features such as trees and walls and their impact on solar access.
The amount of sunlight directed at a window varies according to the time of year, housing density, and orientation. In the southern hemisphere, the angle of the sun makes a low arc across the sky in winter with its highest arc reached in Summer.
North-facing windows tend to not have much direct sunlight at all, and therefore will be a darker but even-lit room. North-facing windows are perfect for people that don’t like too much direct sunlight. North-facing windows receive twice the winter sun than east and west-facing windows, allowing light and warmth into the home. They can be easily shaded from the high summer sun to help keep the house cool. Ideally, the glazing area should be between 10-25% of the floor area of the room
East/West–facing windows tend to be the brightest in the morning/evening, respectively, and the light will be more of a warm golden tone. It receive little sunlight in winter, autumn and spring, but excessive sunlight in summer. It is recommended windows are kept small and well-shaded, particularly those facing west if this does not compromise ventilation. Alternatively, consider using high performance glazing such as low-e or toned glass.
South facing windows receive no direct sunlight in winter and only early morning and late afternoon sunlight in summer. Windows should be kept small, however they can be extremely useful for passive cooling as part of cross ventilation as cooling breezes in summer usually come from the south.
South is a good direction for views as south facing windows require no shading from direct sun or minimal shading above the Tropic of Capricorn.
Key points:
If you love waking up with the sun, you’ll love an East-facing window.
If you love watching the sunset, you’ll like West-facing windows.
If you don’t like direct sunlight, then look for North-facing windows.
And if you want an all-around bright space, go for South-facing windows.
Dealing with poor solar access
Poor solar access can be detrimental to the comfort and energy performance of a home. Along with poor natural light levels, a lack of sunlight can make a home very cold – winter sun might be blocked by neighboring buildings or views may be to the south or west, requiring windows with poor orientation.
There are many innovative designs available to still achieve an energy-efficient house. Selecting windows with improved thermal performance and high-performance glazing is critical to compensate for poor orientation. The use of performance glazing can limit heat gain in winter and maximize heat gain in summer.
High-density areas
When neighboring buildings obscure wind and sun, there are a number of ways you can still achieve an energy-efficient home.
- Avoid full-length windows as the lower part of the window will invariably be in permanent shade – raise the sill height to avoid heat loss through ‘wasted areas’.
- Use high-level windows and vents to create convection currents for cooling
- Use insulation, draught-proofing and window protection to improve the thermal performance where you are limited to solar access