The Stephen D. Home

Passive Design

To design passively means to consider relying on the natural resources of the site as the first and foremost important issue of building.  All energy systems are configured around the maximum use of sunlight, wind, water, and vegetation.  Solar orientation, length to width ratio of the building, massing of energy intensive spaces and appliances, overhangs, and ventilation paths are the pieces that when put together allow for the best possible use of the given resources. In Constructed Wetlands in the Sustainable Landscape (1999), by Craig S. Campbell and Michael H. Ogden: Using Nature to perform tasks that would otherwise be accomplished by energy-intense mechanical and electrical systems has four distinct advantages:1.  Nature is self-maintaining, self-regulating, and self-organizing.2.  Nature is powered by solar energy and chemical energy stored in organic materials.

3.  Natural systems can degrade and absorb undesirable toxic and metal compounds, converting them into stable compounds.

4.  Natural systems are easy to build and easy to operate. Solar Insolation (Incoming solar radiation/ heat) 

• Seasonal sun angles give the exact degree of where the sun will be facing and aiming its energy throughout the day. Maximizing and minimizing the sun insolation in the extreme seasons is a critical way to moderate temperatures throughout the year by using shades, screens, overhangs, trees, and/or recessed windows.
• Thermal mass located inside the building envelope to receive direct sun and store heat during the day, then release it at night to regulate the temperature helps decrease the need for mechanical heating systems.
• Day-lighting is important because it is proven that there are substantial physical and psychological benefits to exposure of natural, free light.

Radiant cooling and heating  Air has a low heat capacity and water has a high heat capacity, which means that water can store hot or cold energy more efficiently than air.  Traditionally, air has to be compressed before it is moved, and the result is moving large quantities of air into a space to regulate its temperature.  Water, on the other hand, costs about 5% as much as air to move, and can be done with pumps. 

• Radiant systems use water to mediate the temperature and can be installed several different ways, whether in the floor, ceiling, or walls.  The standard applications are as follows: concrete core uses plastic tubes buried in the concrete; metal panels use metal tubes attached to aluminum panels and have a very fast response time due to its metal construction; and cooling grids use plastic tubes embedded in gypsum or plaster and are generally used in retrofit applications.
• Trombe walls and thermal massing can passively store heat and release it when the space becomes cooler as an effective way to regulate room temperature at night, decreasing the need for energy intense systems in the cooler seasons of the year.

 Wind, prevailing wind strength and direction that changes throughout the seasons

• The prevailing wind is important because it is a natural force for moving wind. When designing on a site with known wind directions for different seasons, maximizing or minimizing exposure is the key to using this resource.
•  Wind breaks, berms, and other deterrents can all be organic, or vegetative, meaning trees, bushes, grass hills, and green walls.  These can cut down the amount of cold air that penetrates into a building during the cold seasons.
• Cross ventilation, shaded and from the prevailing direction during the warmer seasons can provide the building with cool, clean air.

 H₂OThe main goals for water usage in a building are to reduce the amount consumed, and rethink the wastewater treatment strategy for cleaner, better quality water. 

• Ultra low flow fixtures (toilets, shower heads, sinks, water fountains, etc.) require less water than EPAct-compliant fixtures
• Graywater systems provide the reuse of water from the building, and reduce the unnecessary use of potable (drinkable water), in applications like irrigation of lawns, flowers, trees, and shrubs.  These systems collect, filter, and distribute water from showers, bathtubs, bathroom sinks, washing machines, drinking fountains, condensation pans from refrigeration equipment and air conditioners, hot-tub drainwater, pond and fountain drainwater, and cistern drainwater.
• Rainwater harvesting is the collection, storage, and use of rainwater.  Using rainwater reduces the pressures of limited water supply, stormwater runoff, and flooding. The water is collected from roofs and other catchment devices, and is then stored in a cistern.  After purification, the water is considered very safe and of high quality.

STORMWATER MANAGEMENT  Water, unlike most other natural resources, is in a permanently closed loop.  Before building, the natural flow of water on and around the site should be taken into consideration.  Keeping the original flow of water across the site should be maintained as much as possible.  Through the use of bioswales, constructed wetlands, and pervious pavement systems, the water a building consumes and sheds can be cleaned naturally.     ·         Bio-swales are nature’s water filters that provide direction and containment of storm water runoff, and flooding.  Swales are essentially small creek beds that replace the conventional use of concrete pipes to move contaminated, rain and flood water to water tables.  Through sediment traps and filtration devices, the swale removes harmful pollutants that the vegetation and soil can clean and break down.  Bio-swales are complex filtration systems that have hydrologic, biological, and chemical functions.·         Constructed wetlands are nature’s wastewater treatment systems.  Waste water from the building can be treated through the wetland which performs the same filtration processes as natural wetlands; efficiently removing contaminants from waste water through biological processes. Both capitol and operating costs are far lower than conventional wastewater treatment plants. ·         Pavers and porous pavement are important materials in managing water because surfaces that shed large amounts of water can change the flow of natural ecosystems on site.  Any pavement system that allows water to pass through can help keep flooding to a minimum and keep the soil healthy through ground water recharge. Recycled building materials such as brick, stone, or concrete can be crushed and reused for pathways and ground cover for parking, or outdoor spaces while remaining sustainable and pervious.   Works CitedMost information derived from Dr. Charles J. Kibert, Sustainable Construction, Green Building Design and Delivery