I have expressed dismay in the past that builders of new homes in our area are not getting “with it” when it comes to incorporating the latest thinking and technology regarding energy efficiency.
Builders boast their Energy Star appliances and lower HERS scores, but they are still, for example, installing gas forced-air furnaces instead of heat pumps, gas water heaters instead of heat pump water heaters, and gas cooktops or ranges instead of induction cooktops.
The Geos Community in Arvada provided proof of concept for the all-electric solar-powered, net zero energy home, and homes in that small, privately developed neighborhood have been featured for several years on the annual tour of “green homes.” But no production builder here has picked up on that concept, and when another builder acquired the undeveloped parcels at Geos last year, the first thing they did was bring a natural gas pipeline into the community to serve their new homes, greatly upsetting the happy homeowners of the original net zero energy Geos homes, which purposely have no natural gas lines.
Above is one of KB Home’s all-electric homes in Menifee CA, a smaller city south of Riverside. Not only is every home in that subdivision “net zero energy ready,” but they are tied together in an electric “microgrid,” designed to power itself cooperatively should there be an outage in the larger electric grid.
In the garage you can see both an EV charger and a wall-mounted battery backup system. The small print on the sign reads: “This all-electric, solar-powered home is equipped with smart technologies and a backup battery, plus community microgrid connectivity designed to help maximize home energy efficiency and comfort.”
Meanwhile, here in Colorado, neither KB nor any other builder, to my knowledge, is even offering heat pump HVAC units or heat pump water heaters as upgrades.
Given our commitment to addressing climate change, one of my favorite email newsletters is “Big Pivots,” written by Allen Best of Arvada, The mission of his non-profit is to document, understand and educate about the changes made necessary by climate change.
Among those changes is the transition from fossil-fuel heating of homes and water using natural gas and propane now that electric heat pump units are practical and affordable.
The latest Big Pivots email newsletter (which you can subscribe to at bigpivots.com) was about Crested Butte’s recent decision to outlaw natural gas in new construction. Rather than rewrite what Allen wrote, here is his article with some minor edits:
By ALLEN BEST
Crested Butte, a one-time coal mining town, has now turned its back on natural gas. Town councilors unanimously agreed that any new building erected on the 60 vacant lots cannot be served by gas. Major remodels must be electric-ready. It’s Colorado’s first natural gas ban, although 80 other jurisdictions around the country have taken similar measures.
“There was a lot of talk at council about it being a bold decision, but I don’t see it that way,” said Crested Butte Mayor Ian Billick. “Not only is it what we need to do, but we have all the tools to do it cost effectively.”
Billick arrived at Crested Butte several decades ago as a biologist at the nearby Rocky Mountain Biological Laboratory. Many experiments there have focused on the effects of warming temperatures on existing plants. One experiment involving year-round heat lamps specifically foretells a shift from the showy wildflowers for which Crested Butte is famous to an ecosystem dominated by sagebrush.
Temperatures continue to creep higher, but at more than 8,900 feet in elevation, Crested Butte still has chilly winters. The overnight temperature during January averages 6 below.
The takeaway here is that if Crested Butte is comfortable with the replacement technologies for natural gas, most other places in Colorado should be, too. Instead, builders are still tethering tens of thousands of homes and other new buildings each year to natural gas pipelines.
Denver and Boulder have taken steps to push alternatives. Here and there individual action has occurred. In Westminster, John Avenson in 2017 ordered his natural gas meter removed after maximizing the passive solar potential of his house. (YouTube video tour of John’s home.) In Arvada, Norbert Klebl developed 30 homes without natural gas in a project called GEOS. In Basalt, two affordable housing complexes have been built without natural gas. An all-electric hotel is under construction in Snowmass. North Vista Highlands is slowly taking shape in Pueblo. In Fort Collins, plans have been drawn up for Montava, a 500-unit project.
We have been pivoting slowly, but the transition is accelerating.
Granted, the generation of electricity still causes atmospheric pollution. Emissions will dramatically drop by 2030, however, as Colorado’s utilities close nine of today’s 10 coal-burning units.
Colorado legislators in 2021 passed several laws that collectively seek to squeeze emissions from our buildings. The laws reflect the state’s political makeup. Colorado may be dominated by Democrats, but it’s still a purplish state. In other words, don’t expect a wave of Crested Butte-type mandates such as occurred in California beginning in 2019. We walk on a different balancing beam.
Most important among Colorado’s legislative squeezes is Senate Bill 21-264, which requires Colorado’s four regulated natural gas utilities to incrementally reduce emissions.
The law identifies several pathways. They can, for example, help customers improve efficiency of buildings, so buildings need less gas to provide comfort. They can augment the methane obtained by drilling with methane diverted from sewage plants, feedlots and other sources. The first of their plans will be filed with state regulators in 2023. The bottom line is that the gas companies will have to adjust their business models.
The Colorado Public Utilities Commission has now set about creating rules for evaluating clean-heat plans. In filings beginning last December, real estate agents, home builders and even some municipalities have argued that converting from natural gas will add costs. That was the same message at recent meetings in Montrose and Grand Junction. Their message was simple: Don’t change.
In metro Denver’s more affluent northwest suburbs, Christine Brinker of the Southwest Energy Efficiency Project reports a draft policy would give builders a choice between either all-electric or natural gas with extra energy efficiency.
Unless a way can be found to cost-effectively sequester carbon emissions, natural gas will slowly be phased out in coming decades. Ironically, the arrival of natural gas was one reason that coal mining ended in Crested Butte in 1952 after a seven-decade run.
It’s sad to see elected officials not taking the time to learn about new technology, especially technology that contributes to abating the effects of climate change.
Such is the story unfolding in the city of Arvada, where the city council — historically super friendly to developers — has bought into a false narrative by a developer/builder team that all-electric homes are not affordable or desired by today’s home buyers.
This is happening despite the fact that Arvada is itself home to a well known model of affordable all-electric homes in the Geos Community located west of Indiana Street and south of 72nd Avenue.
The Geos Community was partially built out several years ago without any natural gas lines. Home heating is by geothermal and air source heat pumps. Cooking is on induction cooktops. Heat pump water heaters provide the domestic hot water. Solar panels on each home provide all the electricity needed for these and other needs, making all 26 current homes “net zero energy.”
Before the Geos Community could be fully built out, its original developer was forced into selling due to a divorce settlement. Otherwise the remaining 250 homes — a mix of townhomes and single family homes — would have been built to the same net zero standard. The new developer had promised to do so, as described in a Nov. 17, 2020, post on MileHighCRE.com, but it reneged on that promise and is in the process of installing natural gas lines to the new homes, greatly annoying and angering the owners of the original 26 homes.
The fossil fuel industry duped all of us by promoting methane as a “natural and safe” gas for use in homes. This gas is highly heat-trapping (80-100 times more so than carbon dioxide), prone to explosion and causes many health issues (see Electric4Health.org). During the last decade Colorado added an average of 20,500 residential gas customers each year. BigPivots.com reports that our state now has 1.8 million residential gas customers. That trend needs to be reversed. There’s no need to keep building home reliant on natural gas.
Geos homeowners appealed to Arvada’s city council to deny the developer a permit for the gas lines, but the city declined to do so. The neighbors, however, are not giving up and have 267 signatures (including my own) on a petition to reverse that decision. The City of Arvada has advised the current Geos residents that this issue is closed.
Arvada should be proud that it is the home of the country’s first “geosolar” community which has, among other honors, been featured several times in the Metro Denver Green Homes Tour. I myself have produced narrated video tours of three Geos homes for that tour, which you can view here, here, and here.
As part of its COP 26 coverage this week in Glasgow, CNN will air a segment on Geos as a home building model to be emulated, essential for addressing climate change.
The Geos Community located southwest of Indiana Street and 72nd Avenue in Arvada is a shining example of what’s possible in net zero energy home construction.
All Geos homes are solar powered and have no natural gas service. Heating and cooling is provided by ground source or air source heat pumps. Water heaters utilize heat pumps, not gas, and all the homes and townhouses are built according to passive solar design standards.
Now a developer has bought the remaining land within the Geos Community but is intending to install natural gas service in all the homes they will build. Naturally, the current residents are quite upset about this turn of events and are hoping to convince the City of Arvada not to allow this diminution of the original intent of Geos to be a strictly net zero energy community.
Rainer W Gerbatsch, a Geos resident, in an email to Linda Hoover, Senior Planner for the City of Arvada, expressed concern about the new developer’s plan to deviate from the community’s principles by installing natural gas in future homes. Here is Ms. Hoover’s emailed response:
Thank you for your strong interest in your community. I was forwarded your concerns regarding the new upcoming development in the GEOS Neighborhood and I will do my best to address your comments. The GEOS Development was approved 12 years ago. I took over as the staff planner for this project in 2014 when the previous planner left the City. When GEOS was approved, it was intended to be a sustainable community and Norbert Klebl tried for many many years to obtain the funding to make that happen. To date, the only homes constructed out there are on Block 10 which has a mix of the staggered “checkerboard” single family detached homes and townhome units. This totals approximately 38 units out of the 282 planned. While the existing homes have a number of sustainable features, SunStudios (Architect) and Laudick Engineering are telling us that marketing of this concept has been very difficult in part due to the economics of having a development without gas service and other unique features of this development, such as having custom designed mechanical heating systems, etcetera. Most of the larger home builders want developments that have gas service. As you may know, this development went through a bankruptcy last summer. The new owners are currently in the process of working with a new builder – Dream Finders Homes. As Dream Finders comes on board, they are planning on keeping many of Norbert’s original concepts, but wanting to make some adaptations to make it economically feasible. The lot layout which has the staggered checkerboard placement of single family detached homes in the middle of the block and townhome units on the ends of the block will remain as originally intended. As a result these homes will continue to have the same architecture and passive solar design. In addition, solar panels will be placed on the rooftops and appliances will be energy efficient. These new homes will follow the Building Code to construct energy efficient homes. The building codes adopted by the City already allow various paths/choices to construct very efficient (minimum energy code) all the way to net-zero buildings – the traditional codes were followed to build the first 38 units. It is my understanding that DreamFinders would prefer to have the project served by gas, but are still looking into the economics of this issue.
This development was and still is zoned PUD (Planned Unit Development) which has its own unique design requirements rather than following the standards in the City’s Land Development Code (LDC). The GEOS Design Book states that “architecture should strive for Energy Self-Sufficiency and the avoidance of Fossil Fuels.” It also identifies net zero homes as one of the intended goals (not requirements) and further clarifies that that “goal can be achieved by combining good solar orientation and good insulation with geothermal or solar thermal heat, and photovoltaics.” However, it is silent on the issue of gas service.
As a result, we would allow the development to be built without gas service (just as was done for the first phase of GEOS) provided alternatives were ensured. However, no restrictions were included in the Design Book or on the project approvals that prohibited gas service. Passive systems, energy efficient buildings, heat recovery ventilation are guidelines not requirements.
Here is Rainer’s response to Ms. Hoover’s email:
I am familiar with the background of GEOS and the more recent events. Contrary to your statement that net-zero homes are difficult to sell, recent sales activity of homes in GEOS show just the opposite – there is high interest in these homes resulting in higher than expected returns for the seller and very short listing periods. It would appear that cited developer/builder statements are either uninformed or demonstrate an unwillingness to engage in construction practices that are a win-win situation for the builder, the buyer, and perhaps most importantly, the environment we all rely on. Also, I contacted and asked the architect whether he supported the cited developer/builder statements, and he responded that he did not.
Studies of completed net-zero buildings in Colorado (including GEOS) conducted by SWEEP also show that the initial cost of net-zero, all-electric homes at this time is on par with so-called traditional (polluting) construction. Net-zero construction represents a clear choice once future buyers understand that (1) these homes represent (already at this time) substantial yearly savings in energy use/expenditures (fossil fuel based energy costs will only increase as the cost of natural gas escalates based on the need to curtail and ultimately eliminate gas as a potent driver of climate change), and (2) eliminate health risks related to exposure to gas appliances and fossil-fuel burning heating devices that generate a variety of air pollutants which have been linked to cancer, decreased lung function, heart disease and a host more diseases. While these risks have been recognized for some time, they are finally receiving mainstream media attention. However, resolution is not possible without the engagement of all levels of government with developers/builders on more responsible construction practices. In summary, net-zero construction is currently superior to traditional construction because of reduction in emissions, elimination of health issues traced to fossil fuel based energy use in homes, and escalating future costs of fossil fuels, particularly natural gas.
GEOS’ prominence as a leader in de-carbonized and sustainable community living is recognized locally (we have been visited by members of sustainability committees of several Colorado towns), and nationwide (CNN’s chief environmental correspondent Bill Weir visited GEOS; CNN will be airing a nationwide broadcast on GEOS, highlighting its features as the model for home construction to achieve decarbonization and healthier interior air quality for residents). In that vein, responsible governments on all levels are preparing and committing to road maps with the goal to rapidly reduce emissions in home construction through elimination of fossil fuels, increased efficiency in appliance/lighting and heating/cooling, as well as the production of on-site renewable energy. In order to have an effective road map, commitments are required which mean nothing less than elimination of fossil fuel use in all new buildings. Consider that the IEA has just issued a special report; this statement stands out: Fatih Birol, the IEA’s executive director and one of the world’s foremost energy economists, told the Guardian: “If governments are serious about the climate crisis, there can be no new investments in oil, gas and coal, from now – from this year.”
It is 2021, and permitting a developer/builder team the inclusion of natural gas infrastructure for about 250 new homes, based on questionable developer/builder concerns of perceived marketability or economics, thereby locking in emissions for the life of the buildings, subjecting owners to health risks related to gas pollutants and escalating energy costs (not considering future mandated retrofits based on the trajectory of climate induced changes), is not responsible, sets the wrong signal and constitutes a serious setback in rising to the challenges of the climate crisis.
The City of Arvada has the opportunity and responsibility to address the climate crisis, facilitate the transition from fossil fuels to renewable energy, and protect the health of residents from natural gas pollutants. Both can be realized, simply and effectively, through rapid adoption of policies and building codes that support state and nationwide goals in emission reductions. We urge you to demonstrate your commitment to a sustainable future not only through elimination of the fossil fuel infrastructure for the next phase(s) of GEOS, but through a city-wide commitment to net-zero construction, fossil-fuel free construction.
The Metro Denver Green Homes Tour is every October, but you can take a video tour of one of the best “green homes” of the last 20 years at www.GreenHomeoftheMonth.com. The January 2021 Green Home of the Month is Rainer Gerbatsch’s home in Arvada’s net zero energy Geos Community.
I have the best assignment on the steering committee of the Metro Denver Green Homes Tour — shooting video tours of the homes we choose to feature. Because of Covid, I’m taking that assignment more seriously than ever, because we may not have an in-person tour this year. (The tour is on October 3rd.)
I post these tours (along with the video tours of our listings) on my YouTube channel. Go there to check out some of the more recent tours.
Those videos, however, are limited in what they can convey in 7 to 10 minutes, so I must leave out a lot of what I learn during the lengthy orientation I get from each homeowner prior to shooting the video.
A good example was my tour last Saturday of Jen Grauer and Josh Renkin’s house in Denver. They scraped a house and built from scratch the best example of a “high performance home” I have come across yet — and I’ve seen a lot of high performance homes.
My 7½-minute tour of the house that Jen completed three years ago could not include a lot of what makes it such a good example of sustainability, so I’ll add to it here.
To be “net zero energy,” a solar-powered home like Jen’s has to be super insulated and super efficient in its use of energy. When a home is that tight, indoor air quality has to be addressed to make the home safe. That job is performed by anEnergy Recovery Ventilator (ERV).
The ERV’s job is to bring in fresh air from the outside and to expel bad air while maintaining a healthy indoor humidity level. In the typical home, exhaust fans in bathrooms, kitchens and laundry rooms exhaust air to the outside, thereby drawing fresh air into the house only through whatever leaks exist around doors, windows and other penetrations of the home’s “envelope.” An ERV has one dedicated duct to exhaust air and another to bring in fresh, filtered air. This air is circulated through the house via multiple exhaust and fresh air vents around the home. In addition to maintaining indoor air quality, the ERV transfers some of the temperature (and humidity) of the outgoing air to the incoming air when there is a differential between the two.
Let’s say your home is 70 degrees inside, but it’s 100 degrees outside. The temperature of that incoming air can be reduced to, say, 75 degrees by passing it through a heat exchanger where it doesn’t mix with the outgoing air but acquires some of its temperature. Similarly if the outdoor air is below freezing, the ERV might raise that incoming air to, say, 50 degrees. (I could be way off on these numbers. I’m just trying to convey the concept.)
A conditioning ERV (or CERV) monitors the level of carbon dioxide and volatile organic compounds (VOCs) in the outgoing air. You can set a level that is acceptable (say, 900 ppm maximum) and the CERV will increase the flow of air when those levels are exceeded to bring them back to the acceptable range. Whereas an ERV runs 24/7, the CERV only needs to turn on to bring the levels of CO2, VOCs and humidity down to set acceptable levels. A CERV also has an internal heat pump to add heat or cooling. (See my videos of John Avenson’s and Jim Horan’s homes.)
In Jen’s case, in addition to an ERV, she made sure that the home was built with low-VOC products. For example, instead of using high-VOC particle board, her cabinets are made with zero-formaldehyde birch plywood and her island is solid maple and waterproofed with a zero-VOC oil. Her home has no wall-to-wall carpeting, which typically has VOCs in it. (These items are mentioned in the video of Jen’s house.)
Radon is another pollutant which seeps into every home through their concrete foundation walls and slab-on-dirt. To further improve air quality, Jen installed a radon mitigation system.
In summary, a high performance home can not only save you money in the long run (it costs more to build but nearly eliminates monthly utility bills), it can also create a home than extends your life through improved indoor air quality.
That’s what it’s like for Jim & Patty Horan, who bought their 3-bedroom, 3-bath, 2,135-sq.-ft. home at 15062 W. 69th Place in Arvada’s Geos Community. They paid $525,000 for it three years ago (July 2017).
Like all Geos homes, this one has no gas service. With only 6kW of solar panels on the roof, the home is heated by a ground source heat pump. It draws heat from the earth via a 300-foot-deep loop under the home. The heat pump uses very little electricity during the summer to further cool the 55° fluid in that loop, and not much more energy during heating season to heat that fluid to 100 degrees.
On Saturday, June 27th, Jim Horan gave me a tour of his home which I recorded for this fall’s Metro Denver Green Homes Tour. You can view the video at YouTube.com/jimsmith145.
Geos Community’s website describes it as “Colorado’s first geosolar development” and is the only subdivision I know that’s built entirely “net zero energy.” There are developers building solar-powered communities like KB Home’s subdivision on the northeast corner of Hwy 93 and 58th Ave., but they don’t come close to being net zero.
There’s a term for such homes — “greenwashing,” which Wikipedia defines at “a form of marketing spin in which green PR and green marketing are deceptively used to persuade the public that an organization’s products, aims and policies are environmentally friendly.” I’ve always marveled that those KB Homes were built with many of the solar panels installed on north-facing roof surfaces.
Getting back to the Horans’ home, there’s more to going net zero than having solar panels and a ground-source heat pump. Those features must be coupled with energy saving features so that the limited number of solar panels are enough to meet the home’s energy needs — with energy left over to charge an electric car.
Here are some of those features which I covered in my video tour with Jim Horan.
First and foremost is the passive solar orientation of the building with lots of south-facing windows and a south-facing roof for solar panels. Also, there are overhangs above each south-facing window designed to shade it from the sun during the summer while allow full sun in the winter when the sun is lower in the southern sky.
Next, the building’s “envelope” has to be very tight. That starts with foam insulation blown onto the interior surfaces of the roof and exterior walls, replacing the blown-in cellulose and fiberglass batting typical of tract homes built by other developers. The windows are Alpen triple-pane windows which also have foam-insulated fiberglass framing. (Fiberglass is better for window framing than vinyl – not as prone to aging and warping.)
Those elements make a house too air-tight for healthy living, so an energy recovery ventilator is installed which constantly brings in fresh air, using a heat exchanger designed so that the heat (or coolness) of the air being exhausted is used to heat or cool the fresh air being brought into the house. A heat pump within this device, called a CERV, provides further heating or cooling of that fresh air as needed.
In the townhomes at the Geos Community, the CERV works with an air-source heat pump mini-split instead of a ground-source heat pump to heat and cool the home year-round.
Have you heard the term “indoor air quality” or “sick building syndrome”? It refers to high levels of CO2 or volatile organic compounds (VOCs) which can build up in a home, especially in a home as air-tight as the Geos homes.
The CERV monitors both CO2 and VOC levels in the house and will bring in additional fresh air when those gases exceed the level set by the homeowner. (The Horans have the level for each gas set at 950 parts per million, or ppm.)
What are VOCs? If you can smell it, it’s probably a volatile organic compound. Examples include new carpet smell and, worst of all, cat litter smells.
Two appliances in Geos homes also contribute to their low energy load. One is the Bosch condensation clothes dryer, which pulls in cool, dry air from the room. The air is heated and passed through the clothes; but instead of being vented outdoors, the air travels through a stainless steel cooling device or heat exchanger. It does heat the room it is in, so the Horans choose to dry their clothes on an outdoor line during the summer, even though their heat pump could handle the additional cooling load if they didn’t do that. Home Depot sells the Bosch 300 “ventless” dryer for $989.
The other appliance is the heat-pump water heater. It has a heat pump above the tank which transfers the heat from the room into the water. I’ve written about this product before. Home Depot sells a 50-gallon Rheem model for $1,299which earns a $400 rebate from Xcel Energy and another $300 in federal tax credit if purchased by December 31, 2020. Because this appliance emits cold air, it’s in a pantry which the Horans keep closed in the winter and open in the summer. (I would put it in a wine cellar or in a room with a freezer, which emits hot air — a symbiotic arrangement within one room.)
As you are beginning to gather, building a net zero energy home is best done from scratch, when the additional cost is less than retrofitting a home. (My home is net zero in terms of electricity, but we still burn $30 to $50 of natural gas each month, and it takes twice as many solar panels for my home, which has about the same square footage as the Horans’.)
You may be wondering how much more it cost to build the Horans’ house, which they bought new in July 2017. To answer that, I searched all the comparable homes (2– or 3-story, between 1,500 and 2,500 square feet within 1 mile radius) sold during the summer months of 2017, and I found that the $246 per finished square foot paid by the Horans was actually below the median price ($253 per finished square foot) for the seven comparable sales. And those homes probably pay thousands of dollars per year more for electricity (and gas) than the Horans.
If you want to learn more about Geos community, give me a call at 303-525-1851 or visit the Geos website, www.DiscoverGeos.com.
Cohousing communities have been built in Golden and Boulder, and one will be built in the Geos net-zero energy neighborhood on 69th Avenue, west of Indiana Street, incorporating the same net zero energy design elements described in today’s other post about Geos. Ten members are already signed up, including Norbert Klebl, the developer of Geos. When there are 12, design and construction work will begin.
At www.RalstonCreekCohousing.orgyou can watch some useful videos and learn about their monthly video chats and events. The community will consist of 20 or so units in a U-shaped condo-style building with main-floor common spaces and a courtyard facing Ralston Creek.
If you like the idea of cohousing, check out this one, which has the additional feature of being net zero energy.
I love showing homes in Arvada’s Geos Community to buyers individually, but there’s a live Zoom presentation sponsored by First Universalist Church of Denver next week which will teach you all you need to know about this great community.
The homes and townhouses in this community are not only “net zero,” they are “net positive,” creating more energy than the homeowners use, including when they charge an electric car. The homes are so well insulated that they need no furnace, only a CERV, which also monitors and maintains indoor air quality.
“Passive House” is a concept born in Germany as “PassivHaus” but growing in popularity here in America. Although its primary focus is on reducing the heating and cooling needs of a home through proper north/south orientation, the placement of windows, and roof overhangs, it also includes design elements that make a home better for its inhabitants. It has many other positive impacts as well, including healthier and quieter spaces, greater durability, and greater comfort for inhabitants.”
Prior to the oil embargo of 1973, home builders did not concern themselves much with making homes energy efficient, but that all changed as we quickly realized how dependent we were on foreign countries for fossil fuels to heat our homes and fuel our cars. Homes built before then were poorly insulated, drafty and less healthy. (For example, lead-based paint wasn’t banned until 1978.)
The passive house concept took off in America as a result of that wake-up call. The “Lo-Cal” house created in 1976 consumed 60% less energy than the standard house at the time, and the concept continues to mature.
If you participated in any of the “green home” tours that Golden Real Estate co-sponsors each fall, you’ve learned about various passive home strategies in addition to “active” strategies such as solar power, heat pumps, geothermal heating, and energy recovery ventilators.
When “active” systems are introduced to a home with passive house design, they work more easily to create the ultimate goal of a “net zero energy” home — one which generates all the energy needed to heat, cool and power the home and, perhaps, charge the owner’s electric vehicles. Without passive house design features, you can still achieve net zero energy, but it may require substantially more solar panels to compensate for such factors as inferior orientation, fenestration (windows) and insulation.
You can learn all about passive home technology, including trainings and public events, online at www.phius.org. Also, search “Passive House SW” at www.meetup.orgfor local events.
An excellent example of new construction which combines passive house design with smart active systems in the Geos Community in Arvada, which you can learn about online at www.DiscoverGeos.com. The homes in Geos are all oriented to maximize solar gain in the winter, but also designed for sun shading in the summer. Some have a geothermal heating, while others have air source heat pumps and conditioning energy recovery ventilators (CERVs). The CERVs installed in the Geos homes not only provide heat when needed but also track the level of CO2 and volatile organic compounds (VOCs) in the air and adjust their function to reduce those levels, thereby improving indoor air quality.
None of the Geos homes uses natural gas, just solar-generated electricity.