Silverwood Inc
New Homes and Construction
Answers to Green FAQ'S
What is the advantage of a sealed crawlspace?

A sealed crawlspace is like a "mini basement". It saves energy and contributes to healthier indoor air in the living space. A sealed crawlspace has no vents, the foundation walls are insulated, the ground is covered with thick plastic sheeting and the access door is insulated and weatherstripped. The floor of the living space is not insulated. The crawl remains dry because there are no vents to the outside and the ground moisture is sealed away. Therefore the area is not conducive to mold growth. There is no condensation from the HVAC ducts in summer because no warm outside air is moving across ducts carrying cold air. Again, this promotes a dry crawlspace not conducive to rot, mold and mildew. A small amount of conditioned air is delivered to the crawlspace area from the HVAC system creating positive pressure in the crawlspace. The positive pressure prevents air from the crawlspace being drawn into the duct work and delivered to the living space. Crawlspace air remains in the crawl not in the living areas.
A sealed crawlspace saves energy because the duct work is located in a semi conditioned area. Because the crawlspace walls are insulated and the ground maintains a year round ambient temperature, the crawlspace quickly achieves a temperature within a few degrees of the living area above. This dead air space acts as a buffer between the living space and the great outdoors. No energy is lost in the ducts by forcing warm air through a cold unconditioned area in winter or cold air through a warm unconditioned area in summer. The HVAC is allowed to operate at maximum efficiency.


What about solar mass?


Traditionally, a solar home is designed with a mass characteristic to accompany passive solar construction. If you are looking at this section of the website, you already know that mass is put in place to moderate heat gain during winter days, and to extend the warmth of the sun for a little while into the evening. Using "old solar" technology and design technique, oversized windows or even sliding glass doors would be lined up facing south and the flooring in front of these units would be made of brick or concrete. In many cases it would be proposed that an operable insulation curtain be put in place that could be opened during the day, and closed during the night. From years of designing and building solar homes, we have found that the requirement to live in a masonry and glass box that has to be operated twice daily has not worked out well for many homeowners. Many older passive solar homes are now fully carpeted, fully draped, or even enclosed with solid walls in order to make living spaces more inviting. Passive solar modifications to lifestyle are aimed at the heating season. In the mid-Atlantic, we are finding that it may make more sense to focus more on efficient cooling  rather than near optimal passive solar heating. Our designs use a "passive tempered" approach. We maximize our window units on the South side, and calculate the height of those windows so that the roof overhang will shade them as fully as possible during the warmer months. We have no South facing windows that are not shaded. Since our South facing glass does not go the floor, the interior wall space on those walls is available for lifestyle choices, such as furniture placement. As is requisite of passive design, we adhere to maximizing living spaces on the South, and concentrating storage areas, garages, and sleeping quarters on the North. In the winter, the home warms up quickly as the Sun's heat radiates through the South facing windows, and the central heating system operates for a shorter period of time. Integral to "new solar" design are the advances in efficiency envelope construction we are currently using. By using very high quality window and door units, sealed crawl spaces, sealed attics, and super sealed blown foam insulation, lowered solar heat gain will have its maximum effect, and the homes' cooling systems will perform much better. One of the greatest benefits of the passive tempered home is day lighting. During sunlight hours, the interior spaces of the home are flooded with natural sunlight, and the need to operate electric lighting is greatly reduced. It makes for a very nice place to spend the day!  A final word on mass - If a home owner wants to have a mass characteristic in their residence, our designs lend themselves to such construction and it can be easily added. It won't hurt anything, and it will enhance the passive solar heat cycle to some extent.

Is geothermal heating an option, and how does it work?


Geothermal heating systems are electric heat pumps that use a water loop for heat (and cool) BTU transfer. Water is circulated through a system of pipes which are put in contact with the ground. Instead of pumping heat out of (or into) the air, as in a standard heat pump system, heat is pumped out of (or into ) the ground using the water as a transfer medium. We have found that the best way to achieve ground contact for the geothermal loop is in a vertical drilled well, with multiple ground loops going "up" and "down". The water in the loop contacts the ground, but is sealed away from the sides of the well in geothermal piping. This is called a "closed loop" system. Geothermal HVAC systems are more efficient than air based systems. It is easier to transfer a btu in and out of water than it is to transfer a btu in and out of air. The ground is a more consistent heat source/sink than is the air. We offer geothermal heat and cooling as an option. Because the cost of the systems is measurably greater than air based heat pumps, geothermal becomes a matter of choice and budget.

Do you have gray water systems available?

Gray water systems transfer non toxic waste water to areas that will have less impact on the environment, and hopefully create a secondary use for the water as it soaks back into the earth. A common use for gray water is lawn watering. Bingham Ridge homes use private septic systems. An impact on municipal water filtration and stream water quality will not be made by introducing a gray water system to a home. To the extent gray water will aid in agricultural activities, we will design a system to meet a homeowner's specific needs, given limitations placed on us by the County Health Department. In the area of water conservation, we promote rain water catchment systems wherever possible. By collecting rain water for garden and lawn watering, we can conserve ground water supplies, and save the electricity needed to pump water out of the ground.

Is solar energy used for radiant floor heating?


We heat water for domestic usage using solar panels on the roof, and a storage tank for a pre-heat cycle in the potable system. The water produced by this system is quite hot. Radiant floor heat systems require a moderate hot water supply (around 106 degrees) and a slow flow directed through zoned loops. In many systems, these loops are cased in a concrete floor. Radiant loops can be attached to the underside of a joist floor system as well. This installation will generally require a modification to the sealed crawl space design and insulation envelope, as we do not want to heat the crawl space as a primary zone. Using potable hot water as a source for radiant heat presents some problems. If the radiant circulation system is not run continuously, water in the loops can be stagnate. These issues can be overcome, but it may be best to supply a discrete heat source for a radiant heating system. An issue to remember is that radiant heating will supply heat only. You will still need a forced air system for cooling. Radiant heat in the winter is very pleasant. The floor is warm, and there are no fans blowing. As is the case with geothermal, it will raise the cost of the residence. As an addition to our base criteria, it can be nice. For some, it may mandate living on a concrete floor instead of wood. It all becomes a matter of choice and cost.

Should I use an 18 SEER or higher AC system?

The higher the SEER rating for a heat pump system, the more efficient and quiet it will be. The jump in cost from 14 SEER to 18 SEER is significant. By focusing our design on sealed envelopes, sealed crawl spaces, sealed attics, and good window and door units, the pay back period for the difference in cost between a 14 SEER unit and an 18 SEER unit at today's energy costs is fairly long. The higher SEER unit is arguably superior. Again, it is a matter of budget and desire.
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