Green Building

We took our first green building class in 2003, put on by Southface Institute of Atlanta, originators of the Earthcraft program, an early green building program that was a joint venture between Southface and the Greater Atlanta Home Builders Association. We began building green houses in Atlanta in 2005 and moved to Asheville later in 2005 and became one of the first builders in Asheville to join the North Carolina Green Building Council when it originated. Because Asheville is a “green” City, the organization has been wildly successful and we have been proud to have contributed twelve houses (certified and in process) to their success.

Our approach to green building begins with the building science aspects. Whether we are building a speculative house (customer not identified prior to breaking ground) or a custom home for a particular customer, getting the design details right initially is crucial. Groundbreaking architect Peter Pfeiffer (Barley & Pfeiffer, Austin, TX) has been quoted as saying that 90% of the green details are best influenced at the design stage. Making sure that the ducts are contained in conditioned spaces affects the framing systems. Making sure that the plumbing runs and the HVAC ducts lengths are minimized calls for attention to their placement prior to breaking ground. Reengineering the plans to eliminate unnecessary studs and setting up advanced framing techniques are just a few of the early details that must occur before construction begins.

We own software to do both energy analysis and HVAC sizing (Both Manual J and Manual D). Our energy software package, Energy-10, is particularly useful in doing the initial design and figuring out which techniques are most beneficial. This software does essentially the same analysis that the software the HERS raters use does. Energy-10 is known for its ability to handle passive solar applications as well as the ability to figure out which energy-reduction strategies make the most efficient use of your resources. Energy10 can rank order the best strategies to use as well as tell you those that would never pay back if implemented. Our HVAC software calculates the sizing for the HVAC (Manual J) and also the duct runs (Manual D). We can offer our own independent analysis to the HVAC contractor of the sizing of the unit and the placement of the duct runs. We are the only builder in Asheville with our own energy analysis software, our own HVAC sizing software, and our own blower door to measure air intrusion.

We offer a consulting relationship for all the green building analysis that we can do for you. It is an hourly rate explained further on the Custom Building page under Preconstruction Services Only. In the event we later enter into an agreement to build a home for the client, we credit the fees paid under the professional service agreement to the cost of the home. The green building analysis includes the following:

Energy modeling- using the architectural plans and Energy-10, we model the energy usage of the house and then test alternative energy-saving strategies to determine which are the most beneficial to lower energy usage and lower the carbon footprint. This analysis uses real-world data about your project rather than theoretical models using assumptions that may not be valid for Western North Carolina. For example, we are at 35 degrees latitude, in Climate zone 4, and a mixed-humid climate. Many of the theoretical assumptions might be beneficial for different latitudes or different climate zone or different climate conditions. Also, this analysis shows the interaction of various components which few tools do. For example, assume that the house is built to very airtight standards and super insulated; under those conditions the HVAC system is little used. Given the airtight-superinsulated house, how long will it take to pay back the added cost of a geothermal unit versus using a conventional air source heat pump? Also given the airtight-superinsulated house, how long will it take to pay back the added cost of R-5 windows (U= .20) versus less-efficient less-expensive R.35 windows (U= .28). Without doing this analysis, it is very easy to choose materials for the home that are not optimized for your home

HVAC Modeling-We do a Manual J load sizing analysis to insure the proper size unit for the home. Most HVAC systems are significantly oversized because they are sized based on rules of thumb that assume a leaky house, not the airtight superinsulated ones we produce. Without this empirical evidence, most HVAC contractors upsize the units.  This saves the homeowner a significant amount of money which can be used elsewhere. Not only are oversized units more expensive, they lead to early equipment failure (due to short cycling) and decreased occupant comfort. We also can do a Manual D duct analysis which insures the proper amount of airflow to every room.

Blower door analysis-Because we own our own blower door, we use it as many times as we can during the building process to insure that the home is airtight as possible early on. Conventional blower door analysis is done at the end of the process when the home is complete. If the home then does not pass the test, remediation measures must be undertaken (tear out drywall?) to get the home to pass so that it can be green-certified.

We utilize many different green building techniques. Because we build both spec houses and custom houses and in varying price points, not all these techniques are used on every house, but all of them and more are available to use on any homes we build for you.

Crawlspaces and basements:
Crawlspaces– We have done several closed crawlspaces (also called sealed crawlspaces and conditioned crawlspaces) both with our own crews and utilizing outside contractors. The purpose of them is to reduce moisture and partially condition the crawlspace.

Basements– We have built both poured-wall (crawlspace-type-foundations) and whole basements from Insulated Concrete Forms which are super-insulated. The basements have all been finished off to make conditioned space. The exterior walls of an ICF structure are minimally R-22, which understates the true R value due to lack of credit for airsealing.

We use 2”X 6” exterior walls as well as energy-saving framing techniques such as two-stud corners, ladder-T’s for interior-to-exterior-wall intersections, and other thermal bypass techniques.

Extreme care is taken with airsealing because as much of 50% of the eventual heating and cooling load is caused by leaks in the exterior envelope of the house. These leaks, once covered with insulation and drywall, become a permanent part of the house, causing needlessly high heating and cooling bills for the life of the house.

We use 2X6 exterior walls which allows more insulation and less frequent studs. By using 6” studs, we can put in thicker insulation, starting with R-19. We currently are using blown-in-blanket insulation which achieves R-23 in the side walls. Our ceiling insulation is generally R-55 since a high proportion of the heat loss is vertical.

Windows, no matter how good, are the weak insulation areas in the exterior walls. Even the best windows generally achieve no better insulation values than R-5 whereas the rest of the exterior wall may be achieving R-23. So the amount of glazing in the exterior wall is a balance between the reduction in energy efficiency and the increase in beauty and views desired by most homeowners. Sunshine entering houses through the windows both heat the interior and have the capability of fading textiles. We use high-efficiency windows which achieve the lowest solar heat gain and highest insulation vales available for the price point houses we build.  Much work is being done in this area by manufacturers and R-10 windows are now available, though pricy.

Heating and Air Conditioning:
Asheville’s climate is heating-season-dominated due to its elevation. As a result the HSPF ( Heating Season Performance Factor) is more important than the more-familiar SEER (Seasonal Energy Efficiency Ratio). We substantially exceed the requirements of the NC HealthyBuilt House program. Our HVAC systems often are 9.0 HSPF and 14 SEER yielding dramatically lower utility bills.

We utilize an EPA-certified clean-burning (72% efficient) wood fireplace which serves two purposes. First is the beauty of a wood-burning fireplace that homeowners enjoy. The second purpose is as a supplemental heat source. The fireplaces have two sets of blowers; one is to supply heated air to the area around the fireplace; the second set of blowers is connected to the HVAC system so that warm air can be circulated to the rest of the house with the flip of a switch.

Water Heater:
We use high-efficiency water heaters (.91EF or better). Additionally we have used heat pump water heaters that are used to primarily heat the water with standard less-efficient resistance elements only used sparingly.

IAQ (Indoor Air Quality):
We have used most of the traditional outside-air-introducing techniques (Aircycler, damper-driven introduction, as well as ERV’s [Energy Recovery Ventilators]) as well as the exhaust-only techniques of constant and intermittent exhaust. The techniques used vary in price dramatically and therefore vary with the price point of the home being built. Based upon the price point of the home you want to build we will make a recommendation.

The HealthyBuilt home inspector visits the home on several occasions as the home is being built to verify and test particular subsystems. The output of this process, once the home is complete, is a certification that the home complies with the program and a score is derived. Paperwork is sent in that will enable the homeowner to get a 5% energy deduction from Progress Energy, the local utility provider.

All of the techniques thus far are site-independent, meaning that these techniques can be used on any home. The site-dependent strategies are solar, wind, and micro-hydro. We are looking for customers that want us to build houses using these techniques. We’ll build the house and work with your choice of the solar, wind, or water vendor.

Some of the green features in Mountain Realty Builders’ homes are contained in the following list. Because we build in several price ranges, not all features are available in every home; which features are in which home is a matter of the agreement between the homeowner and the builder.

Mechanical systems
All heating and air ducting in conditioned spaces
All ducts mastic sealed to prevent air leakage-no more than 5% leaks
Heating/cooling system properly sized for efficiency by Manual J
Motorized damper introduces outside air to replace stale inside air (or ERV)
MERV 9 pleated filters installed on HVAC system
Ducting protected from debris and dust during construction
High efficiency hot water heater
Programmable thermostat
High efficiency HVAC system (Min 13SEER and 7.55HSPF) Upgrades available.

Erosion control plan to prevent washouts
Onsite trees protected from damage during construction
New/replacement trees added at rate of 12/acre
Drought-resistant trees and shrubs indigenous to NC
Drought-resistant planting plan given to homeowner
Drought-resistant sod provided standard
Bait termite system used rather than poisoning soil.

Low flow showerheads and faucets standard
Dual-flush toilets standard
Energy Star dishwasher standard
Bath exhaust fans in baths exhaust >50CFM to outside
Formaldehyde-free particle board/MDF used for trim throughout whole house
Formaldehyde-free particle board/MDF used for closet systems throughout whole house
Low/No VOC paints used inside house
100% formaldehyde-free insulation used throughout house

Concrete countertops in kitchen
EPA-certified 72% efficient wood fireplace with central HVAC option can be used to heat entire house.

Exterior Construction
Construction waste recycled
Framing, insulation package, air intrusion independently verified by an outside 3rd party.
Use of Insulated Concrete Forms for basement walls (poured foundation walls)
High efficiency Andersen or Peachtree windows with low U values and low SHGC values. Double-paned low-e argon-filled windows.
Conditioned crawl space for mold-resistance
2X6 exterior walls with R-19 insulation
R-30 batt insulation in the floors
R-38 to R-55 blown insulation in the ceiling
Radiant barrier sheathing in the attic reduces heat buildup by up to 30 degrees
Zero formaldehyde OSB used in subfloor
Locally recovered aggregate and sand
Window and door flashing installed in addition to air/vapor barrier
Window and door gaps foam sealed
Door and window sill sealers used in addition to window and door flashing
Hardiplank siding and trim with 40 year manufacturer’s limited warranty
Extensive air sealing and weatherstripping to minimize air and moisture intrusion.

In 2009 we became Department of Energy Builder’s Challenge builders. Builder’s Challenge builders have enhanced access to the work of the DOE national labs like Oak Ridge National  Labs and high-powered teams like Building Science and Davis Energy. Through them we have the ability to get early notice of cutting edge energy-saving research which we can then apply to the custom homes of our customers.

Most Western North Carolina Green Home builders have not certified anywhere close to twelve homes with the local green agency (Western North Carolina Green Build Council). We do not know of any other Western North Carolina Custom Green Home builders that own their own blower doors. No other Asheville, North Carolina (Asheville, NC) Green Home builder performs energy analysis to our knowledge. Nor do any Haywood County Green Builders own their own blower doors. The combination of our experience and unmatched capabilities separate Mountain Realty Builders from other green builders.

Recently we became Certified Green Professionals through the new NAHB (National Association of Home Builders) Green program. As a result, we can now build your green home to either the NAHB standard, the Western North Carolina Green Building Council standard, the Environments for Living program recently reintroduced by Masco Corporation, or the original Earthcraft standard. If you have a particular project in mind that will use enhanced building science techniques, we would love to discuss the project with you.