A Short and Sweet Building Science Teach-In for
GREEN RIVER COMMONS
Green building is not so much a standard based on a check list as an orientation towards the totality of the building process. Designating a building as “energy efficient” roughly equates to describing an automobile as “good”. At Wright Builders, Inc. and Green River Homes, LLC, we have set new standards of performance, durability and indoor health through exploration and adoption of leading proven technologies and research.
All building construction is a bit more brown than green, really, because of the energy it takes to produce a structure. Our goal at Green River Commons is to:
Make the lifetime operation of your home perform at or above its specifications, to offer you a path to Net Zero energy, provide you with products that perform at the highest in their class, and to tread lightly on the planet’s future. We hope a few definitions and details will help you, too, to become more comfortable, discerning, and knowledgeable.
1. SEER = Seasonal Energy Efficiency Rating, a federally calibrated number that indicates the relative efficiency for the equipment. SEER 12 is good, 18 and above is excellent.
2. HERS Rating = Home Energy Rating System, one of two well recognized measurements of a home’s energy and efficiency performance. Based on a scale of “100”, the lower the number, the better the building’s performance. A HERS rating of 55 is required to meet compliancy with the Massachusetts energy stretch code. The Green River Commons buildings have an initial rating (based upon the building design, specified windows, insulation, HVAC, ERV, lighting and appliances) of 41 for the 2 bedrooms and 45 for the 1-bedroom units. A “0” rating indicates Zero (Net) energy usage, which can be achieved with these buildings by adding Photo Voltaic electric panels to make up for the electricity usage. The PV panels can be added to all units. Wright Builders' buildings always exceed minimum energy code standards by significant margins, and our homes outperform their HERS initial ratings, an uncommon accomplishment for some.
3. ERV = Energy Recovery Ventilation. This air exchange appliance exhausts stale air from bathrooms and laundries and replaces it with filtered outside air, recapturing the heat of cooling in the exhaust air through tiny air chambers. Generally, they run on a timed cycle or constantly, are quiet, and have a very Low current draw. ERV’s are the key to healthy air in a high performing building. At Green River Commons, these units will provide the needed air circulation to heat and cool some of the bedroom areas.
4. Blower Door Test is a pressure test on your home during construction and upon completion to determine if it is performing to its designed specifications.
5. ACH = Air Changes per Hour. This indicates the number of times per hour the house leaks its contents of air. An older home might be 5 ACH, or leaking its contents every 12 minutes. The Gold standard for high performance buildings is 1.0 to 1.3 ACH. Wright Builders has achieved rates as low as 0.43 ACH in new and renovated buildings. Clearly, reducing the air changes is the key to reducing costs and increasing comfort, because these air changes are what we used to call “drafts “!
6. Air Sealing is the process and methods for helping to minimize leakage, and includes acoustical caulking at various important framing joints, spray foam around the floor system perimeter, foam around windows and doors, no duct work in attic spaces, and full foam sealant on top of the upper floor ceiling for insulation is installed
7. P.V. (Photovoltaic) The electricity generating panels can be mounted on the structure’s roof (or sometimes elsewhere) and, with no moving parts, generate electric current from the sun. They perform at a range of efficiencies depending on the cloud cover, but the climate in Northampton is excellent for solar generation year-round. The panels have no moving parts, and perform even if periodically covered in snow. The direct current is changed into alternating current at your electric service panel and used in your home. Excess is sent back into the grid and used at the nearest location calling for power. Each month, your electric bill is reduced by the amount you generate, and any excess is purchased by the power company at the RETAIL rate.
8. Net Metering is a Massachusetts provision that allows for electricity processed through a bi-directional meter, to flow in and out of your home’s system freely and at the same price in and out, such that you only pay for the amount of electricity you use that is in excess of what you generate. If, on an annual basis, you generate more than you use, then the utility will purchase the remainder. You can also give it to any charity or person served by the same utility company.
9. R-Value is the measurement of the resistance to heat loss. A higher number is better. The code required R-19 wall in 2 x 6 construction usually consists of fiberglass batt insulation, which does not provide an effective air seal, and is an inferior installation. Using Class I cellulose fiber (recycled and fire rated news print fiber), is vastly superior because it provides a more effective air seal. But, still, that R-19 wall is really only an R-11 assembly because of all the wood involved that provides too much thermal bridging.
10. Net Zero is an indication that energy usage over the course of a year balances out between usage and solar generation. It is NOT an opportunity to be casual about consumption, but rather the opposite. There are actually no net zero buildings, but rather, potentially net zero families and occupants! It’s up to you.
11. Thermal Bridging materials contact between the inner surface and outer surface, which causes a transfer of heat and cold, diminishing the effectiveness of insulation. The answer is a full separation called a thermal break.
12. Thermal Break describes the process or materials that disconnect or de-couple the interior and exterior surfaces. All Wright Builders dwellings incorporate a full thermal break, utilizing several different strategies and materials.
13. VOC = Volatile Organic Compound. These ingredients occur in many products, paints, finishes, cleaning products and solvents, are made from petroleum distillates, and because they are volatile, the curing process for these paints involves the petro-chemical evaporating, with health consequences. So Non-VOC paints means that the polymer chemistry occurs without these harmful ingredients. Still not suitable for use without adequate ventilation, certainly! Actually, some of the worst offenders for these chemicals can be new furniture and rugs.
14. No Added Formaldehyde products contain only the naturally occurring formaldehyde that is in the natural product. Wood, in its natural state, actually contains this material, so it is not quite accurate to state that something is formaldehyde-free. Almost, but not quite.
15. Basement Floor and Wall Insulation provides for a full thermal break between the ground and the concrete, in order to reduce heat loss and condensation. Even those 10-15-degree differences between air temperature and ground temperature, like a dripping faucet, lead to substantial heat loss over time, as well as supporting mold and mildew. Our levels allow the concrete to contribute, through passive storage, tot eh sustainability and resilience of the home.
16. ENERGY STAR is the federal EPA standards and programs designed to encourage energy conservation. Wright Builders has been an ENERGY STAR partner for many years, following a pledge to build to, or exceed, all ENERGY STAR requirements in all homes we build. Under the ENERGY STAR program, much improved and expanded since 2008, certain equipment qualifies for rebates to the builder, which is used to partially offset the higher costs of the better equipment. 3rd party testing is integral to the program, to ensure the rebates and subsidies are earned in the performance of the building.
17. Heat Pump. These devises, run on electricity, are used to leverage the electric consumption through a compressor and condensation cycle. When one runs an air conditioner, cool comes into the room, and heat is expelled. Heat pumps run on the same concept, leveraging the electricity approximately 3:1!
18. Mini-Splits. These heat pumps, running at very high efficiency, have all the compressor machinery outside, and only a filtration and air delivery unit inside. Mitsubishi and Dakin are among the leading brands, utilizing VRV technology. This technology, Variable Refrigerant Valve, allows the equipment, really moment to moment, to right-size the amount of cooling or heating that is needed by the building’s occupants, and then produces just that amount. A teaspoon or a cup full, depending!
19. Heat Pump Domestic Water Heating. Using similar heat pump technology, the hot domestic hot water is brought to temperature by scavenging incidental waste heat in the loft storage areas of the homes, at a nearly 3:1 advantage of electrically heated water.
Note: This information is accurate at time of preparation, but will be adjusted from time to time and may be changed, as it affects Green River Commons at any time without notice.
Green River Homes, LLC
Developed by Green River Homes, LLC
Built by Wright Builders, Inc.