Energy Efficient Homes: Getting Down to Zero, Part 1 (of 2)

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1 Energy Efficient Homes: Getting Down to Zero, Part 1 (of 2) Link 1: By Barbara Ballinger Feb 10, 2017 Editor s Note: The title image for this article was provided by Joseph Kennard and reflects a Joseph Kennard Architects house project in Milton, Mass. Zero Energy Homes help home owners pare energy use and cut costs but getting to that point requires following forward-thinking experts check list. You can cherry pick materials and systems to curtail energy use in a residential and multifamily home and building. But constructing the entire envelope to bring costs down to zero requires a more intensive design and construction process. Originally dubbed Zero Net Energy Homes, the genre was rebranded by the U.S. Department of Energy without the Net. The goal remains similar. Despite these types of structures being built around the globe, there s still confusion about how to achieve best results. Several experienced architects and energy efficient proponents shared these points six this week and seven next week.

2 1. Know what it means to get off the grid. Zero Energy Homes are tied to a community s (electric) grid, which tracks a home owner s energy consumption in the same way a bank calculates a client s funds. On sunny days, solar photovoltaic (PV) panels on the homes produce energy, and what s not used is sent to the grid so the home owner gets credit on their account. On cloudy or cold days, the home owner withdraws energy, the equivalent of taking out funds from their account. If the house was designed properly, the owner will hit the goal of a zero balance by year-round. One exception is if they paid for an initial meter hookup, though some communities don t charge to encourage residents to pare energy consumption, says Joe Emerson, a homeowner in Bend, Oregon, who built his first Zero Energy Home in 2012, and has followed up with several others. He also writes about the topic online at Zero Energy Project. Diagram of solar off grid system present by home photovoltaic and solar equipment. 2. Start with the right site for passive solar gain. The big first step is to choose a site that takes maximum advantage of the sun s energy to provide the equivalent of fuel for a home. That means having few trees and other obstructions that block light on the home s south side, but having some on the north side to buffer it from cold air and wind entering in winter. The best designs have one of the two long sides along the south so more windows can be placed to capture sunlight, along with properly sized overhangs to block strong rays, says Ryan Shanahan, a senior green building consultant with Earth Advantage in Portland, Oregon, which certifies green-built homes and multifamily dwellings. In making such decisions, good tools and services are available from companies such as Solmetric to measure sun, shade, and test PVA performance results, he says.

3 3. Do energy modeling for cost-effectiveness. How many energy-conserving features are incorporated, including how many solar PV panels and their size, may be tough to decide. Consider these options. There are an increasing number of software programs that do the work for you. Third-party energy consultants will also model data as a valuable subcontractor on your team, says Shanahan, whose Earth Advantage firm handles such work. If you follow this approach, choose someone who understands local weather conditions. Jacqueline Nunez, a Boston developer with WonderGroup, did so when she started planning her Allandale Street project that will feature 20 town homes and condos in the Boston area and which the Boston Planning and Development Agency board approved last fall. Nunez hired engineer Jeffrey Rhodin s Sustainable Energy Analytics firm to help drive decisions that would lead to Net Zero, LEED Platinum, and Fortified Construction standards, the latter to withstand severe weather. Architect and founder Ted Flato s Lake Flato Architects firm in San Antonio is so committed to using as little energy as possible that it has two engineers on staff who specialize in this work. Architect Joseph Kennard whose eponymous firm is based in Boston, has been interested in sustainability since the firm was founded in He consults with outside engineers and builders on such challenges as window and door products, layered insulation packages, and mechanical systems. The firm is currently designing a Zero Energy Home in the suburb of Milton, Mass., salvaging materials from a house torn down on the site, and using metal wall and roof products to make it durable for the long term. While built on a tight budget for his clients, the house serves as a prototype for affordable techniques. We work to determine the right amount of product (return on investment) so the home owners can reduce energy costs without overspending to achieve that goal. Increasing durability and maximizing energy savings will prove beneficial well into the future as costs keep soaring, Kennard says. 4. Seal and insulate the envelope. Emerson suggests thinking of a Zero Energy Home as a six-sided box that has been sealed and insulated on all sides to avoid letting hot and cold air in and out. To do this requires selecting the best constructed members walls, floors, ceilings, windows, and doors, and insulating them as another line of defense. Walls should be double thick, and each 1-foot thick with blown-in insulation between them. How much insulation? The R-value depends on an area s climate. The same rule of thumb applies to insulation used in an attic with the highest possible R-value sought, but again dependent on location. These days triple-pane windows with the best U-value which in this case is the lowest possible number offer a gold standard, but some double-pane windows with a very good U value can produce similar results for less money. The best way to know if a package is tight is to have an energy consultant conduct a blower-door test. Sealing and insulation offer another benefit to make a house more durable against moisture, which causes the majority of defects, Shanahan says.

4 5. Minimize thermal bridging. Energy is also lost through thermal bridging, usually because of poor construction, inferior insulation, or both. Double wall construction with insulation between and rigid foam insulation on the outside of a home s framing will minimize or remove the possibility, which also leads to mold, Emerson says. 6. Use the sun to heat a hot water system. A thermal hot water system that relies on a storage tank and PV collectors can provide a home s hot water supply. Choose either an active system that may feature a pump that circulates water directly through the collectors and into the home, or circulates a nonfreezing heat-transfer fluid through the collectors and a heat exchanger, or a passive system that doesn t include the circulating pump, but is less costly. It s downside is that it may be less efficient. Solar panel for hot water system on roof. Next week, more ideas will follow to fashion a Zero Energy Home.

5 Energy Efficient Homes: Getting Down to Zero, Part 2 (of 2) Link 2: By Barbara Ballinger Feb 17, Pick an energy-efficient heating and cooling system. Also referred to as an air source heat pump, the best choice works in each season to move air in the right direction. In summer, it takes heat from inside the house and sends it outside, and in winter it takes cold air that comes in and heats it. Buy the most efficient one according to industry HSPF (heating seasonal performance factor) and SEER (seasonal energy efficiency ratio) standards. Note: HSPF or heating seasonal performance factor is a term used in the heating and cooling industry to measure an air source heat pump s efficiency. SEER or seasonal energy efficiency ratio standards offer another important measurement for the efficiency of air conditioners. central-air-conditioning 2. Include an energy-efficient, fresh air supply. While a tight house is the goal, a sealed box causes its own set of problems the absence of fresh air, which can be unhealthy. The solution is to include an energy-efficient ventilation system, known as ERV for Energy Recovery Ventilation. This system exchanges and treats incoming air by cooling and dehumidifying it in warm weather and preheating and humidifying it in cool weather. We like to say in the industry, build it tight and ventilate it right, which some of the earliest Zero Energy Homes didn t do, says Ryan Shanahan, a senior green building consultant with Earth Advantage in Portland, Oregon, which certifies green-built homes and multifamily dwellings. Besides eliminating energy use, it will help improve air quality by paring moisture that can lead to mold, increased asthma problems, and other health issues. Do more by picking no- or low-voc (volatile organic compounds) paints, adhesives, sealants.

6 3. Select energy-efficient appliances and lighting. Making these kinds of smart choices has become more common, even for more traditionally constructed homes. Look for the EnergyStar label. Even appliances that once were considered energy guzzlers like dryers have been redesigned to save energy. Lighting can also play a huge part in reducing energy use. New federal standards require lighting manufacturers to sell bulbs that meet minimum efficiency standards, and the most efficient are LEDs. These have come down in price, had their color temperatures or light quality improved, don t include mercury, and are dimmable, says Shanahan. In some communities, LEDs are given away, as Joe Emerson has found. Emerson is a homeowner in Bend, Oregon, who built his first Zero Energy Home in 2012, and has followed up with several others. He also writes about the topic at Zero Energy Project. Boston architect Joseph Kennard also suggests home owners be thoughtful about the number of appliances and lighting fixtures they add into any single home since they end up not using all perhaps, they should do without a microwave they would rarely use for a steam oven, or give up a second wall oven. The same restraint can apply to lights. 4. Factor in up-to-date on incentives and tax credits. Many home owners remain concerned that a Zero Energy Home will cost more at the front end. Industry experts like Shanahan put the additional cost for a passive solar house at 5 to 10 percent higher than a comparable sized less efficient design. But costs can be pared from the start by using incentives and tax credits, which are still available in many areas for solar PV panels, solar hot water tanks, and energy-efficient appliances. The extra dollars can be wrapped into a mortgage since more green financing options are available. For information, see the Department of Energy s Database of State Incentives for Renewables and Efficiency. Kennard, who says many incentives and credits are still available in Massachusetts, likes to show clients how the savings can curtail their costs and lead to more breaks at the state level. 5. Go ready- or off-the-shelf rather than custom made. Home owners and their pros don t have to re-invent the wheel, so to speak. More companies are developing house plans that you can use as is or tweak. Builder and designer Ted Clifton founded Zero Energy Plans to offer plans that range in price according to square footage. The plans list specifications for different climates. Facades veer toward the traditional but a few are modern, which has become more popular, Clifton says. But be cautious, says Kennard, who believes it s important to engage experts who have been working on such projects for a while and who know what to pick and how to combine systems so they work for the long term. You don t want to deal with water and mold issues down the road when you have tight buildings. You need proper air exchanges for good balance, he says.

7 6. Get ahead of the pack. More communities, cities, and states are studying the advantages of initiating Zero Energy requirements. California has passed a law that requires all new construction to be Zero or near Zero by Why not help build a house of the future rather than an outmoded house? says Emerson. Your clients already are able to have their houses certified for a relatively low cost, often even less than 1 percent of the budget, says Shanahan. Earth Advantage offers several certifications, from LEED for homes to EnergyStar, and Passive House PHIUS+, the latter a passive house certification that represents the most efficient energy standard worldwide. 7. Consider valuable aesthetics, too. There s no reason that high efficiency should shortchange looks. I wanted my project on Allandale Street to be aesthetically beautiful; why I felt a contemporary exterior was best, says Jacqueline Nunez, a Boston developer with WonderGroup, who has planned her Allandale Street project to feature 20 town homes and condos in Boston. Kennard, too, favors contemporary designs, and his current project features anodized painted metal standing seam siding and roofing; a less costly option would be cement board siding with asphalt roof shingles, he says. Bottom line: In pursuing this niche, home owners benefit the overall built environment and gain a house that offers a high degree of comfort, healthful air quality, more quiet due to its tighter package, lower energy costs, and greater resilience so the house can cope better all the time and especially during a power outage. And more good news is that more home owners are considering these types of choices, Kennard says.