written by:
September 28, 2011

Project Manager Brad Liljequist chronicles the building of the zHome, a ten-unit townhome in Issaquah, Washington—the first multifamily zero-energy community in the United States. Part 2: Building REALLY green... It's easier than you think.

Forty percent. That’s the share of total CO2 emissions each year in the US that comes from energy used in buildings. Building operations—heating, cooling, lighting, and everything else inside the walls—are the single largest generator of carbon dioxide in the country. It’s an easy thing to forget about, sort of like background noise. But it’s there, humming along, 24/7.

Not for the faint of heart: the ultimate spreadsheet. We spent three long meetings just figuring out what were reasonable lifestyle assumptions for the zDwellers, and this was the result. At the end of the day, achieving zero net energy will be up to the
Not for the faint of heart: the ultimate spreadsheet. We spent three long meetings just figuring out what were reasonable lifestyle assumptions for the zDwellers, and this was the result. At the end of the day, achieving zero net energy will be up to the residents.
2 / 9
More design integration at work—here we’ve pursued deep daylighting into the homes, with a high clerestory in each unit. This was taken on a very cloudy, rainy day on one of the north facing units. The home is completely comfortable without lights on, pro
More design integration at work—here we’ve pursued deep daylighting into the homes, with a high clerestory in each unit. This was taken on a very cloudy, rainy day on one of the north facing units. The home is completely comfortable without lights on, providing obvious living and energy benefits.
3 / 9
Our R-38 wall section. Rockwool insulation is placed in the 2x6 cavity, and 3.5 inches of continuous expanded polystyrene insulation is screwed to the outside of the oriented strand board shear wall. A benefit to this exterior insulation is that the therm
Our R-38 wall section. Rockwool insulation is placed in the 2x6 cavity, and 3.5 inches of continuous expanded polystyrene insulation is screwed to the outside of the oriented strand board shear wall. A benefit to this exterior insulation is that the thermally conductive bridge of the wood studs is broken by insulation. Even a thin layer of exterior insulation can make a big difference.
4 / 9
A mechanical marvel, our ground source heat pump. We’ll go more granular on this in a future blog. I show it here because it’s our single most important conservation item.
A mechanical marvel, our ground source heat pump. We’ll go more granular on this in a future blog. I show it here because it’s our single most important conservation item.
5 / 9
LED lights have really come of age in just the last year or so. When we were in schematic design they didn’t seem like a very cost effective technology for us, but when it came time to spec the lights, we were really amazed to see how far they had come. T
LED lights have really come of age in just the last year or so. When we were in schematic design they didn’t seem like a very cost effective technology for us, but when it came time to spec the lights, we were really amazed to see how far they had come. The light quality is outstanding, and really hard to differentiate from halogen bulbs.
6 / 9
Even small things matter. Here we’ve installed switched outlets, color coded black, to make it easier for residents to turn off phantom loads—those things that continue to draw power when they are turned "off." No more cluttery power strips!
Even small things matter. Here we’ve installed switched outlets, color coded black, to make it easier for residents to turn off phantom loads—those things that continue to draw power when they are turned "off." No more cluttery power strips!
7 / 9
Performance-testing the home with a blower door and sealing it well is perhaps the lowest hanging fruit in the world of building energy efficiency. The blower door depressurizes the house and helps to find leak points. We sealed our homes to nearly twice
Performance-testing the home with a blower door and sealing it well is perhaps the lowest hanging fruit in the world of building energy efficiency. The blower door depressurizes the house and helps to find leak points. We sealed our homes to nearly twice what is required by code.
8 / 9
Tom Marseille, one of our energy leads and nationally known energy expert, thinking deep thoughts about a zero-carbon future.
Tom Marseille, one of our energy leads and nationally known energy expert, thinking deep thoughts about a zero-carbon future.
9 / 9
zhome post2 1

One of the core environmental benchmarks of zHome is achieving zero net energy and zero net carbon emissions. We are achieving this with a number of conservation technologies which reduce energy use by about two-thirds of that of a typical townhome. We then offset the remaining third with solar panels mounted on each zHome roof. The extra energy these panels generate during the summer will offset the amount of supplemental energy the units will need during the cold, dark Northwest winters.

Not for the faint of heart: the ultimate spreadsheet. We spent three long meetings just figuring out what were reasonable lifestyle assumptions for the zDwellers, and this was the result. At the end of the day, achieving zero net energy will be up to the
Not for the faint of heart: the ultimate spreadsheet. We spent three long meetings just figuring out what were reasonable lifestyle assumptions for the zDwellers, and this was the result. At the end of the day, achieving zero net energy will be up to the residents.

Figuring out how to get to zero net energy and zero net carbon emissions at a cost accessible to the mainstream market was not an easy task. A subgroup of our design team wood-sheded for many hours in a series of meetings at the David Vandervort offices. The stars of the show were Tom Marseille, WSP Flack and Kurtz managing principal, energy expert, and Cascadia Green Building Council board member, and Chuck Murray, then of the WSU Energy Program and now with the State of Washington Department of Commerce, where he leads updates to the State Energy Code.

More design integration at work—here we’ve pursued deep daylighting into the homes, with a high clerestory in each unit. This was taken on a very cloudy, rainy day on one of the north facing units. The home is completely comfortable without lights on, pro
More design integration at work—here we’ve pursued deep daylighting into the homes, with a high clerestory in each unit. This was taken on a very cloudy, rainy day on one of the north facing units. The home is completely comfortable without lights on, providing obvious living and energy benefits.

The design that emerged through those hours combined two core conservation strategies that cut our energy use in a one-two punch: thick, highly insulated, very tightly sealed walls (R-38 walls and R-63 ceiling for you techies), and a ground source heat pump system that is three times more energy efficient than the best forced air furnace.
Our R-38 wall section. Rockwool insulation is placed in the 2x6 cavity, and 3.5 inches of continuous expanded polystyrene insulation is screwed to the outside of the oriented strand board shear wall. A benefit to this exterior insulation is that the therm
Our R-38 wall section. Rockwool insulation is placed in the 2x6 cavity, and 3.5 inches of continuous expanded polystyrene insulation is screwed to the outside of the oriented strand board shear wall. A benefit to this exterior insulation is that the thermally conductive bridge of the wood studs is broken by insulation. Even a thin layer of exterior insulation can make a big difference.
A mechanical marvel, our ground source heat pump. We’ll go more granular on this in a future blog. I show it here because it’s our single most important conservation item.
A mechanical marvel, our ground source heat pump. We’ll go more granular on this in a future blog. I show it here because it’s our single most important conservation item.
LED lights have really come of age in just the last year or so. When we were in schematic design they didn’t seem like a very cost effective technology for us, but when it came time to spec the lights, we were really amazed to see how far they had come. T
LED lights have really come of age in just the last year or so. When we were in schematic design they didn’t seem like a very cost effective technology for us, but when it came time to spec the lights, we were really amazed to see how far they had come. The light quality is outstanding, and really hard to differentiate from halogen bulbs.

A sprinkling of other things round out the picture, including 100% LED and fluorescent lighting, in-home energy monitors, heat recovery ventilators, super efficient appliances, hydronic in-floor heat distribution, and natural daylighting. And then of course the solar panel production completes the package.

Even small things matter. Here we’ve installed switched outlets, color coded black, to make it easier for residents to turn off phantom loads—those things that continue to draw power when they are turned "off." No more cluttery power strips!
Even small things matter. Here we’ve installed switched outlets, color coded black, to make it easier for residents to turn off phantom loads—those things that continue to draw power when they are turned "off." No more cluttery power strips!
At the end of the day what I am most impressed by is how relatively simple this all ended up being. None of the technologies are avant-garde. What is perhaps most innovative about zHome is the bringing together of all these things under one roof to meet a profound and world changing benchmark—zero net energy and carbon neutrality. Zero-carbon buildings for the mass market are possible today, and they will only get easier in the years to come. I strongly believe it’s time for us to stop fretting about how we’re going to deal with climate change and ocean acidification, and move forward positively and hopefully with the solutions we have at hand. We can do it!
 

Performance-testing the home with a blower door and sealing it well is perhaps the lowest hanging fruit in the world of building energy efficiency. The blower door depressurizes the house and helps to find leak points. We sealed our homes to nearly twice
Performance-testing the home with a blower door and sealing it well is perhaps the lowest hanging fruit in the world of building energy efficiency. The blower door depressurizes the house and helps to find leak points. We sealed our homes to nearly twice what is required by code.
Tom Marseille, one of our energy leads and nationally known energy expert, thinking deep thoughts about a zero-carbon future.
Tom Marseille, one of our energy leads and nationally known energy expert, thinking deep thoughts about a zero-carbon future.

Join the Discussion

Loading comments...

Latest Articles

45 dva 2270 persp1 cmyk 0
The prospect of retirement doesn’t just signal the end of a career; it offers the chance to recalibrate and re-prioritize in life.
July 25, 2016
18
You don’t have to choose between sustainable energy and curb appeal.
July 19, 2016
jakemagnus queensland 1
Each week, we tap into Dwell's Instagram community to bring you the most captivating design and architecture shots of the week.
July 06, 2016
content delzresidence 013 1
Each week, we tap into Dwell's Instagram community to bring you the most captivating design and architecture shots of the week.
June 29, 2016
abc malacari marwick stair 01 0
A simple set of stairs is a remodel’s backbone.
June 28, 2016
Design Award of Excellence winner Mellon Square.
Docomomo US announces the winners of this year's Modernism in America Awards. Each project showcases exemplary modern restoration techniques, practices, and ideas.
June 27, 2016
monogram dwell sf 039 1
After last year’s collaboration, we were excited to team up with Monogram again for the 2016 Monogram Modern Home Tour.
June 27, 2016
switch over chicago smart renovation penthouse deck smar green ball lamps quinze milan lounge furniture garapa hardwood
A strategic rewire enhances a spec house’s gut renovation.
June 26, 2016
young guns 2016 emerging talent coralie gourguechon treviso italy cphotos by coralie gourguechon co produced by isdat planche anatomique de haut parleur1
Coralie Gourguechon's paper objects will make you see technology in a whole new way.
June 26, 2016
green machine smart home aspen colorado facade yard bocci deck patio savant
Smart technology helps a house in Aspen, Colorado, stay on its sustainable course.
June 25, 2016
Compact Aglol 11 television plastic brionvega.
The aesthetic appeal of personal electronics has long fueled consumer interest. A new industrial design book celebrates devices that broke the mold.
June 25, 2016
modern backyard deck ipe wood
An angled deck transforms a backyard in Menlo Park, California, into a welcoming gathering spot.
June 24, 2016
dscf5485 1
Today, we kicked off this year’s annual Dwell on Design at the LA Convention Center, which will continue through Sunday, June 26th. Though we’ve been hosting this extensive event for years, this time around is particularly special.
June 24, 2016
under the radar renovation napa
Two designers restore a low-slung midcentury gem in Napa, California, by an unsung Bay Area modernist.
June 24, 2016
Exterior of Huneeus/Sugar Bowl Home.
San Francisco–based designer Maca Huneeus created her family’s weekend retreat near Lake Tahoe with a relaxed, sophisticated sensibility.
June 24, 2016
light and shadow bathroom walnut storage units corian counter vola faucet
A Toronto couple remodel their home with a special emphasis on a spacious kitchen and a material-rich bathroom.
June 24, 2016
Affordable home in Kansas City living room
In Kansas City, an architecture studio designs an adaptable house for a musician on a budget.
June 23, 2016
modern lycabettus penthouse apartment oak vertical slats office
By straightening angles, installing windows, and adding vertical accents, architect Aaron Ritenour brought light and order to an irregularly shaped apartment in the heart of Athens, Greece.
June 23, 2016
kitchen confidential tiles custom cabinetry oak veneer timber house
A modest kitchen addition to a couple’s cottage outside of Brisbane proves that one 376-square-foot room can revive an entire home.
June 23, 2016
feldman architecture 0
Each week, we tap into Dwell's Instagram community to bring you the most captivating design and architecture shots of the week.
June 22, 2016
Blackened timber Dutch home
A modern dwelling replaces a fallen farmhouse.
June 22, 2016
hillcrest house interior kitchen 3
Seeking an escape from bustling city life, a Manhattan couple embarks on a renovation in the verdant Hudson Valley.
June 22, 2016
angular
Atelier Moderno renovated an old industrial building to create a luminous, modern home.
June 21, 2016
San Francisco floating home exterior
Anchored in a small San Francisco canal, this floating home takes its cues from a classic city habitat.
June 21, 2016
modern renovation addition solar powered scotland facade steel balcony
From the bones of a neglected farmstead in rural Scotland emerges a low-impact, solar-powered home that’s all about working with what was already there.
June 21, 2016
up in the air small space new zealand facade corrugated metal cladding
An architect with a taste for unconventional living spaces creates a small house at lofty heights with a starring view.
June 21, 2016
young guns 2016 emerging talent marjan van aubel london cwai ming ng current window
Marjan Van Aubel makes technology a little more natural.
June 21, 2016
urban pastoral brooklyn family home facade steel cypress double
Building on the site of a former one-car garage, an architect creates his family’s home in an evolving neighborhood of Brooklyn.
June 20, 2016
Modern Brooklyn backyard studio with plexiglass skylight, green roof, and cedar cladding facade
In a Brooklyn backyard, an off-duty architect builds a structure that tests his attention to the little things.
June 20, 2016
the outer limits paris prefab home living area vertigo lamp constance guisset gijs bakker strip tablemetal panels
In the suburbs of Paris, an architect with an eco-friendly practice doesn’t let tradition stand in the way of innovation.
June 20, 2016