The escalating price of energy today, over-development of our farms and woodlands, and global climate change, sustainable design has increased in popularity and demand. Projects that are designed using sustainable principles may cost a little more. However, through the life of the building, cost savings is achieved through lower utility bills. Generally, sustainable buildings use less energy, release fewer toxic emissions, and reduce uncontrolled storm water runoff creating a more eco-friendly building.
The reuse of an existing building is an obvious and credible sustainable approach. Reusing an existing building applies far less new materials and energy than building new structures. Preservation of existing open spaces and woodlands is also achieved through renovating building that are already standing. The work required in a building renovation can easily incorporate new green materials and building techniques.
The start of each building project begins with the study of its site. As architects, we look at the indicators inherent in each individual site. Situating a building on its site in a way that minimizes its environmental effect will, for example, create less storm water run-off. There are several ways of preserving the open space on the site. They include: control of topsoil erosion, rainwater collection, rain gardens and plant selection.
Control of topsoil erosion during and after construction can be achieved by the implementation of permeable materials such as porous paving. Rainwater collection devices help delay and disperse the rainwater. Building rain gardens decrease erosion by providing a place to collect and store rainwater until it can be slowly released back into the soil. If the water can be slowly released into the soil, it can be absorbed and slowly filter into the aquifer below to the groundwater. Conversely, if the rainwater is quickly released, it may overflow and fill retention basins and storm sewers, flow into our streams and rivers and ultimately out to sea. Lastly, the selection of plants should be carefully considered. Native trees and plants are favored over foreign plants, which have different water and soil requirements. Low water consuming plants and trees should be considered and may be of benefit the site.
Daylighting is implementing sunlight to light a space rather than electrical lights. Daylight reduces electrical consumption and has been proven to improve occupants’ health, happiness and productivity. Daylighting is most efficiently achieved by orienting the building along a north-south axis, toward maximum southern exposure. Through the use of windows, clerestories and light shelves, natural light can be used to make a building environmentally efficient.
Heating and Cooling
There is a delicate balance in heating and cooling a building. Sustainable principles must be implemented minding the exterior climate of the building. To control the air comfort in a building, one can employ solar heat, double glazed wall construction, natural ventilation, geothermal, as well as highly efficient HVAC systems.
Solar heating uses radiation from the sun to passively heat the building. This concept works extremely well and must be utilized in concert with large overhangs to prevent overheating in the summer months in our climate. The overhangs shade the windows in the summer when the sun angles are high and allow sunlight to pass through the windows during the winter when the sun angles are low. This allows the solar radiation into the building during the cool months, and excludes the radiation from the building during the hot months.
Double glazed walls are normally placed on the southern façade and incorporate an exterior layer of glass, an air space, and an interior layer of glass. The system uses the stack effect (warm air rises, cool air sinks) to heat and cool a building. Openings in the glass are placed high and low in both layers of glass. During the summer, the high windows are opened on the interior, catching the rising warm air and releasing it out of the building. In the winter, the sun warms the air between the faces of glass, and then enters the building as warming air. Natural ventilation passively cools the air in a building. It employs operable windows that, when open, create a cross-ventilation effect. Natural ventilation also provides fresh air to improve the health of its occupants.
The geothermal system involves drilling wells into the earth. Water in pipes is pumped to the wells. This takes advantage of the earth’s constant temperature (generally 55 degrees F) and uses the earth as a giant heat sink. The water is then sent through a heat exchanger, either preheating or cooling the air or water for the building’s HVAC system.
High-efficiency HVAC systems reduce heating and cooling cost. These systems cost more initially. However, they cost less to operate and therefore often have a lower lifecycle cost.
A final thought on controlling the air temperature in a building is to incorporate a vestibule. This also helps to reduce heating costs. A vestibule creates a heat trap, so when the exterior door is opened, only the heat within the vestibule can escape. The heat from the remainder of the building is trapped by the interior vestibule door.
Alternative Energy Systems
In the United States, buildings alone use 36% of the total energy consumed and 65% of the electricity used. This alone is motivation to choose alternative, more environmentally friendly energy sources. Alternative energy systems commonly employed make use of the environmental staples of sun and wind.
Solar power uses photovoltaic panels made of silicon. When sunlight hits these panels, it creates electricity. Solar panels require a backup power source. The first of two power backup sources is to tie the solar power system into the community’s electrical provider’s system. On a sunny day, any excess electricity generated is added to the power grid of the local provider. When electricity cannot be generated at night or on a cloudy day, the consumer can draw the power from the grid. If more power is added to the power company’s grid during a billing period then taken, the provider must pay the consumer for the excess. The second way to achieve a power backup is to use a battery source that has been charged with the excess power generated. This system is more expensive and generally only used in rural situations.
Wind energy is created in a wind farm. The wind turns a propeller which in turn generates electricity. In some areas, wind power is available from the local energy provider at an additional cost, although with more and more wind farms starting up and the technology increasing, the additional cost is becoming less.
The introduction of renewable and recycled materials to a building is sustainable design guiding principle. Examples of renewable or recycled materials are bamboo flooring, recycled carpets, and cellulose insulation. Wood logged from a certified forest is also considered a green material, although it is generally more expensive and difficult to obtain. Composite woods are made from recycled woods and plastics. They generally have a longer lifespan and require less to maintain.
The energy efficiency of a building is an issue that is carefully studied. Selecting the proper insulation, high-efficiency windows, occupancy sensors and energy rated light fixtures combine to make a great difference in the energy rating and efficiency of a building. The two types of insulation used with sustainability in mind are blown cellulose and spray foam. Blown cellulose is a good choice because it is made from recycled newspaper and has a high R-value. Spray foam is considered sustainable and when applied correctly, creates a very tight building envelope which prevents air infiltration and lowers HVAC load and usage.
High-efficiency windows save energy. They have a high U value rating and are made of two or even three layers of glass with argon gas in the cavities. Properly sealing these windows with caulk and weather stripping can prevent further air infiltration into the building. Certain considerations should be made when selecting light fixtures. It is advisable to select energy star rated fixtures as well as switch from traditional incandescent bulbs to compact florescent bulbs, which use less energy. Light-emitting diodes or LEDs are another alternative. LEDs use less electricity and have a dramatically longer lifespan than other bulbs.
Raphael Architects is committed to green design. Since the 1980s, Principal Michael Raphael, AIA, has incorporated green ideas into his designs. Raphael Architects’ most recently completed sustainable project, the Crist residence, incorporates many of the discussed sustainable ideas. The project includes bamboo flooring, clerestories for daylighting, geothermal heating, natural wood siding and trim, and blown cellulose insulation, to name a few. Michael also co-chairs the Central Bucks County Chamber of Commerce Architecture and Environment committee, which once a year holds a sustainable design lecture to educate area architects, builders and homeowners on sustainable design.
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