Customized Unity Xyla 212 Sits Softly on the Land

xyla 212

Artist’s rendering of our standard Unity Homes Xyla 212.

Dan Farrell and Melora Kennedy have long been interested in nature conservation. So when they wanted to build a healthy, comfortable, energy-efficient home — close enough to town that he could walk or bicycle to work—a friend, builder and energy consultant, Mark Snyder, suggested they call Unity Homes. Dan works for the Vermont Chapter of the Nature Conservancy as their Conservation Information Manager/GIS Analyst. Melora teaches preschool and kindergarten. The “GIS” in Dan’s title stands for Geographic Information Systems: a science which lets us visualize, question, analyze, interpret and understand data to reveal relationships, patterns, and trends. In the conservation context, GIS would come in handy in evaluating the impact his new home would have on his sloped, 8.9 acre parcel of land, with its old field species and natural plantings — some edible — as well as diverse wildlife crossings.Screenshot 2014-06-23 10.06.14 Unity’s low-waste off-site fabrication and rapid on-site assembly — coupled with its natural materials, extraordinary energy efficiency, and energy-sipping mechanical systems — will all help to reduce the carbon footprint on the sensitive landscape. Their Xyla 212, customized for a walkout, is heated and cooled with an air source heat pump and an optional ERV (Energy Recovery Ventilator) to condition air with minimal energy loss. Both HRV (Heat Recovery Ventilator) and ERV systems are vastly more energy efficient than plain ventilation systems or exhaust-only systems with no heat or energy recovery. Despite its higher up-front cost, Dan chose an ERV system for its edge in operating efficiencies, air filtration, degree of comfort (through greater humidification/dehumidification control) and environmental impact.

air pohoda ashp

The Air Pohoda ERV used in the Farrell home in a special housing devised by our Building Systems team.

Unity’s standard HRV system is designed to recover approx 80% of the heat in the air that is being exhausted from the house, while the ERV (Energy Recovery Ventilation system) is expected to recover over 90%. Given the ERV’s added efficiency, there would be a relatively short payback period on its premium cost over the standard HRV system. In comparing the ventilation systems, the ERV units are expected to save about 1315 kWh per year over the HRV system. At $0.15/ kWh, that comes to almost $200 per year at the current electric rate, with those savings continuing to rise as electricity rates increase. The Return On Investment calculator projects an 11-year payback on the $3,000 additional investment over the cost of a comparable HRV system.  (Source: EPA Greenhouse Gas Equivalencies Calculator.) IMGP7792But for Dan and Melora, it wasn’t just a matter of dollars and cents. Framing it more in conservation terms, the 1,315 kWh per year saved by their ERV over the HRV, is equivalent to 102 gallons of gas, 97 lbs. of coal or 21 barrels of oil. Saving that energy would be the carbon equivalent of 23 tree seedlings grown for 10 years or 0.75 Acres of forest grown in one year. The 2-bedroom, 1-bath Unity Xyla, with its super-efficient 1,028 SF first floor space plan and optional 939 SF walkout level, celebrates the lagom values at the heart of all Unity Homes. Roughly translated, lagom is a Swedish word meaning “not too much, not too little —  appropriately balanced.” The home is neither too big nor too small, but just right perched lightly on its steeply sloped site and in-balance with its surroundings. work in progress Xyla 212Entry is from the up-slope side (and future patio) directly into the living area, which is open to the eat-in kitchen and second bedroom. Down a short hallway and adjacent to bedroom two is the master bedroom and common bath. Dan and Melora plan to leave the ground floor, with its separate down-slope entry, unfinished for the time being, but it will eventually have a rec room and second bath. With the home fabricated off-site and assembled on-site over late spring/early summer, the Farrells expect to be in their home by mid August.

Unity Homes: Indoor Air Quality and Comfort

unity homes kitchenYou can live 21 days without food, 7 days without water, but only a few minutes without air. Every day we take 21,600 breaths; that’s nearly 8 million breaths of air a year. By weight, we take in more air than food: 4,500 times our own weight in an average lifetime.*

On average, we spend 90% of our lives indoors, and approximately 2/3 of that time is spent at home. Today’s health conscious consumers will pay a premium for healthy, natural foods, but often give less thought to indoor air quality or overall healthiness of their homes. A recent McGraw Hill Construction report, “The Drive Toward Healthier Buildings,” finds that most homeowners turn to family, friends or coworkers for advice on home products and practices, with few requesting advice from the builders, remodelers and architects who know most about how these decisions might affect occupant health.

However, homebuyers are increasingly concerned about the Indoor Air Quality (IAQ) of their homes. Pollutants like mold, radon, carbon monoxide and toxic chemicals are receiving greater attention than ever as poor IAQ is linked to a multitude of health issues. Some pollutants cause health problems such as sore eyes, burning in the nose and throat, headaches or fatigue. Other pollutants cause or worsen allergies, respiratory illnesses, heart disease, cancer, and other severe long-term health issues. At high concentrations, pollutants such as carbon monoxide, can be fatal.

Given how important air is to life, let’s examine perhaps the most important attribute of Unity Homes, and properly built high-performance homes in general, which is how they can help you breathe easier and live healthier.

air pohoda ERV

Air Pohoda’s Ultima 240E i-ERV uses an Enthalpy heat exchange core

To start, only low VOC (Volatile Organic Compounds) materials and finishes are used in the construction of Unity highly-insulated, tightly-sealed, energy-efficient homes, resulting in exceptional levels of indoor air quality. Because of their extraordinary air-tightness, the indoor air is continuously replenished with fresh and conditioned air, reducing the energy losses that typically come from whole house ventilation. This is accomplished by the use of a standard Heat Recovery Ventilator (HRV) or optional Energy Recovery Ventilator (ERV) with adjustable humidification and dehumidification controls. 

Regardless of which ventilation system is chosen, Unity homes come standard with air-source heat pumps (for heating and cooling). When properly installed, an air-source heat pump can deliver one-and-a-half to three times more heat energy to a home than the electrical energy it consumes, according to the U.S. Department of Energy.  This technology loses less humidity in the winter than with forced hot air/furnace systems that scorch the air at high temperature—driving off its moisture—making an outboard humidifier consume more energy to replenish it. Finally through filtration, allergens and other pollutants can be removed, making indoor air considerably healthier than outside air.

Why build tight houses that require sophisticated ventilation systems, you ask? There are many myths held by the public (and by many builders as well) surrounding the false notion that houses need to breathe. This bogus theory holds that houses can be too tight and that air leakage or “natural ventilation” dries everything out and keeps the air quality healthy. But as Green Building Advisor.com points out, “…air leaks mean you’ve lost control of air movement…air and moisture can be forced into wall and ceiling cavities where water vapor condenses and fosters the growth of mold.”

Additionally, according to Green Building Advisor.com,

“Warm air exiting the top of the house can draw in cold air to replace it, wasting heat and energy. In many ways, uncontrolled air movement wastes energy and increases the risk of long-term damage to building components. Effective air and moisture barriers reduce those problems, but they come with a few caveats: Tight houses need mechanical ventilation to ensure a supply of fresh air to keep people healthy.”

a Unity Homes Xyla 212

Artist’s rendering of a Xyla 212.

And while we’re on the subject, what exactly is “fresh air?” Most would assume outside air is fresh air, but whether you live in the city or the country, outdoor air carries pollutants in the form of gasses, droplets, and particles. This includes pollution from cars, trucks, airplanes, industry, tractors plowing fields, wood and crop fires, ground level ozone, and allergens like pollen. Indoor air, too, can contain a host of pollutants from combustion sources like stoves and furnaces, to high VOC building materials and furnishings, to household cleaning products and radon, to name a few. All of these pollution sources can cause health problems if not mitigated through green building practices and sophisticated air handling technology.

Unity Homes, and other quality high-performance homes, help you breathe easier and live healthier by using only green materials and finishes, by sealing out unwanted moisture, dirt, dust, insects and allergens that can lead to health problems and costly repairs, and by conditioning and filtering incoming air. At the same time, Unity’s well insulated and tight building envelope reduces overall heating and cooling costs, and adds comfort by eliminating drafts and temperature variations.

Moreover, while a Unity Home conditions your indoor air, its low-waste, precision offsite fabrication and super-efficient energy performance thereafter works to lower its impact on the outside air—which we all share—as well.

xyla 212 under construction

A Unity Homes Xyla 212 under construction in Vermont.

Our newest Unity, a Xyla 212 with an ERV in Montpelier, Vermont will be featured in our next newsletter.

Read more about what steps to take both to reduce the risk from existing sources of indoor air pollution and how to prevent new problems from occurring in EPA’s “Care For Your Air: A Guide to Indoor Air Quality.

*Source: http://minkukel.com/visualize-it/every-breath-you-take/