According to the U.S. Greenbuilding Council, approximately 75% of U.S. energy is generated from fossil fuels. Fossil fuels are byproducts of oil, coal and gas. When processing or using these fuels, there are impacts that affect our environment. Burning these fuels releases pollutants, such as nitrogen oxide, sulfur dioxide and carbon dioxide into the air, leading to conditions such as smog and global warming. The goal of building a LEED certified green home is energy and resource efficiency, which in turn will minimize the use of these fuels. Using less energy in the home will have a trickle down affect on the environment. Burning less oil or gas to heat a house will lead to reductions in smog and greenhouse gases. In addition, green homes are less expensive to heat, cool and light, so they also become less expensive to operate. Designing the best systems for the home’s mechanicals, such as heating, cooling and plumbing become one of the most important long term features for continuing energy savings. There are many ways of achieving this.
In the case of heating and cooling equipment, there are no certified “plug and use” systems that have a green label. Systems are designed as a result of a homeowner’s desire for comfort and savings and their unique ideas to combine systems. Green building design means good engineering design, including taking advantage of the natural resources. Siting involves careful evaluation of solar access and vegetation. Southern facing windows will generate passive solar heating during the winter days, reducing the demand for a heating system. Deciduous trees (trees whose leave drop in the fall) will block these windows from the summer sun, allowing the house to remain cool. Evergreens will remain green all year round and block the northern side from cold winds. Passive solar, deciduous trees and evergreens will all be used to complement the solar panels being proposed in Three Groves Ecovillage.
The alternatives for heating or cooling savings result in using a combination of passive measures and active ones. Passive measures can be achieved, as stated, through southern facing windows. Or, techniques such as natural ventilation, which do not provide the entire cooling load, but reduce the intensity of the HVAC system. Active measures are the load produced from the solar panels.
Even if you use solar, you will have some heating system for backup or an air conditioning system for days the natural ventilation is not used. For heating and air conditioning systems, a few important terminologies need to be defined.
SEER (Seasonal Energy Efficiency Rating) ratings are an indication of the efficiency on air conditioners. According to the NAHB (National Association of Home Builders), the national minimum is 13.0 seer - the lowest rating on a system. The higher the rating, such as 14.0 or 18.0, the more efficient the system. For central furnaces, AFHU (Annual fuel utilization efficiency) is an indicator of how efficient a system is in using fossil fuel or electricity over the course of a year. The national minimum is 78%, but systems can be as efficient as 97%, converting nearly all the fuel to useful heat. In the design process, the system should not be over sized for the house. A larger system does not make it more efficient. Efficiency and size work together for savings. In addition, ductwork should be installed within the thermal envelope of the house and not on outside walls. Cold outside walls convert to heat loss as it flows through the ductwork. Sealing the system with approved mastic diminishes the problems of leaking. Joints in sections of ducts, if not sealed properly, can leak as much as 30% of the air being moved by the blower.
“Greening” your plumbing is an opportunity to realize important water and energy savings that quickly payback on your investment. Basic plumbing and new integrated systems offer high efficient technologies for opportunities to reduce and/or recycle water in a home. Integrated systems pay off in reduced water usage. Integrated systems allow for the capture of “graywater”, which is water from sinks and showers, to be recycled and used in toilet flushing or treated for landscape watering. It further keeps water out of the sewage system, reducing the facilities burden.
Faucet and showerhead aerators and pressure assisted toilets are alternatives to replace older fixtures that use less water in the process. Also, plumbing fixtures that use less water often require smaller plumbing lines or less plumbing over conventional fixtures, leading to increased savings on installation. Major water using appliances, such as dishwashers and washing machines, should bear the ENERGY STAR® label, which cut energy costs drastically over those without this rating. Heat recovery, positioned properly, is an opportunity to use the heat from waste water, as it transfers heat from drain lines into nearby areas, such as closets. Items such as on-demand pumps get hot water to taps faster, eliminating running water while waiting for it to become hot. One technology used since the 1960’s has been perfected, called a Radiant slab systems. This can be used in heating a home, thru a process called conduction. Conduction is the movement of heat thru a solid material, with floor finishes in this application being either tile or wood, both good conductors of heat.
Choosing sustainable materials for the actual pipes installed in the home reduces pollution in the groundwater, drinking water and the air. Materials such as cast iron, concrete and plastics such as HDPE should be used. PVC should not be considered as it has serious environmental problems, such as the release of toxic dioxin, one of the worst known carcinogen and pollutants, and it is not recyclable.
One of the least expensive energy saving techniques is insulating water pipes and the water heater, which are usually contained in an unconditioned space, such as the basement. For the pipes, it prevents hot water from cooling off and cold water from heating up. An insulated blanket keeps the water heater from losing heat thru the tank walls, therefore keeping the water hot longer.
There are many items that can be chosen when building a green home. Not one item is the single answer, but may play an intricate part in the whole picture. By combining these features, they produce energy efficiency, resulting in lower utility bills. The goal at Three Groves Ecovillage is to reach “net zero energy”, meaning no utility bills. Our purpose is to share as much information as we can and to enlighten others as to what we are choosing for our homes and what makes them different.
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