Hammer & Hand http://hammerandhand.com INCITING EVOLUTION IN BUILDING THROUGH SERVICE, CRAFT AND SCIENCE. Fri, 17 Apr 2015 15:15:19 +0000 en-US hourly 1 Two weeks chock-full of passive house and living building! http://hammerandhand.com/field-notes/two-weeks-chock-full-of-passive-house-and-living-building/ http://hammerandhand.com/field-notes/two-weeks-chock-full-of-passive-house-and-living-building/#comments Tue, 14 Apr 2015 18:30:05 +0000 http://hammerandhand.com/?p=6502 Many of us at H&H are resurfacing from two weeks full of presentations, dialogue, and community building with our Passive House and Living Building colleagues. On the evening of March 25, a capacity crowd of Passive House enthusiasts, green building practitioners, and building industry leaders joined us at the Bullitt Center’s Discovery Commons space to... Read more »

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Many of us at H&H are resurfacing from two weeks full of presentations, dialogue, and community building with our Passive House and Living Building colleagues.

On the evening of March 25, a capacity crowd of Passive House enthusiasts, green building practitioners, and building industry leaders joined us at the Bullitt Center’s Discovery Commons space to witness the launch of North America’s new passive building standard, PHIUS+ 2015. James Connelly (Living Building Challenge Manager at the International Living Future Institute), Leah Missik (Built Green Program Manager at Master Builders Association of King & Snohomish Counties), and Joe Giampietro (Board Member of Passive House Northwest) were on hand to make remarks congratulating PHIUS and PHAUS for its work and anticipating increased collaboration moving forward.

Our own Sam Hagerman, co-host of the party with PHIUS/PHAUS, emceed the evening and introduced PHIUS Co-Founder and Executive Director Katrin Klingenberg to party-goers. Katrin made the official unveiling of the standard, summarized its climate-specific and cost-optimized approach, and shred the technical underpinnings of PHIUS+ 2015. An exciting night!

Katrin Klingenberg at PHIUS+ 2015 Launch Party | Hammer & Hand

Katrin Klingenberg speaking to the crowd about PHIUS+ 2015.

The next day we dove into the PHnw6 conference on Seattle’s waterfront. H&H’s Dan Whitmore taught a 4-hour intensive passive builders training during the day, and Skylar Swinford and I delivered an evening address entitled “Why Passive House? Because Buildings Can Restore” as a warm-up act to Lloyd Alter’s (of Treehugger fame) excellent keynote, “In Praise of the Dumb Home” – a critique of our society’s tendency toward techno-fascination and gadgetry that can short-circuit passive and other green building fundamentals. The next day was full of excellent Passive House workshops, including Sam’s standing-room-only presentation about H&H’s high performance wall assemblies:

Sam Hagerman at phNW Conference 2015

Günter Lang of Passivhaus Austria delivered an uplifting address entitled “Sustainable Cities Go Passive,” somewhat tempered by Steve Hallett’s keynote, “Passive Houses, Efficiency Traps, and Some Unexpected Comments on Carbon,” a thought-provoking and challenging presentation about the Jevons Paradox, Peak Oil, and what lessons we can take from ecology to teach us about what we as species/society might expect in coming decades. Sobering stuff.

On April Fools Day we switched gears, joining the sold-out throng at the Living Future unConference 2015 at Seattle’s Sheraton for an inspiring three days of sessions about the Living Building Challenge and Living Communities. Dan and I had the pleasure of co-presenting a session with Dale Mikkelsen entitled “Conservation First!” making the case for the complementary nature of Passive House and the Living Building Challenge (via LBC’s Net Zero “Energy Petal”). Dale, who also won the 2015 Living Building Challenge Heroes Award at the conference, is a pivotal player in the inspiring Univercity green community project in Burnaby BC. Among many highlights at the conference were the plenary sessions with Ibrahim Abdul-Martin (Director of Community Affairs at the NYC Department of Environmental Protection) and Jason McLennan (CEO of the International Living Future Institute, our neighbors here at the Bullitt Center) and the “This One Goes to 11” interview of Bullitt Foundation President Denis Hayes by Brad Kahn.

Zack at Living Future 2015 Conference | Hammer & HandEric Corey Freed, VP of Global Outreach with International Living Future Institute (left) and H&H’s Zack Semke at Living Future unConference 2015. Photo credit: Danielle Barnum.

Skylar Swinford and Hammer & Hand Wall Assembly

Passive House consultant Skylar Swinford shares H&H’s high performance building wall assembly mock up at Living Future unConference 2015.

My favorite quote from Denis came in response to a question about the daunting challenges we face in transforming our building stock fast enough to be climate friendly. Denis joked that as a younger environmentalist he sometimes measured a lecture’s success by how many participants wanted to commit hara-kiri at the end. Then one night his wife Gale joined him at a lecture. On the way home she remarked on the respect that she knew Denis held for natural selection and the power of competitive advantage.

“So tell me, what’s the survival value of pessimism?” she asked.

What gives Denis hope today? Our ability as a people to turn like a school of fish when we need to. He points out that it seems to take a big slap to the face first. Pearl Harbor was one such slap, resulting in unprecedented shifts of behavior, personal sacrifice, and mobilization of effort and ingenuity society-wide. Sputnik was another, launching the mind-blowing technological and logistical stretch that landed humans on the moon in the age of the slide rule. There’s precedent for major, coordinated human response to crisis.

We surely have some climate-related slaps coming our way which will test our species’ capacity for collective response. But what’s the survival value of pessimism?

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Loft Remodel Transforms Kitchen From Commercial to Cozy http://hammerandhand.com/field-notes/loft-remodel-transforms-commercial-kitchen-into-cozy-kitchen-for-young-family/ http://hammerandhand.com/field-notes/loft-remodel-transforms-commercial-kitchen-into-cozy-kitchen-for-young-family/#comments Mon, 13 Apr 2015 22:20:51 +0000 http://hammerandhand.com/?p=6489 During the colorful century-long history of this Portland building, the space at the heart of our loft kitchen remodel has served many purposes, most recently as a commercial kitchen for alternative school students. Today, it is reborn as a hip residential kitchen for a young urban family. A couple years ago Hammer & Hand helped... Read more »

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During the colorful century-long history of this Portland building, the space at the heart of our loft kitchen remodel has served many purposes, most recently as a commercial kitchen for alternative school students. Today, it is reborn as a hip residential kitchen for a young urban family.

A couple years ago Hammer & Hand helped transform the second floor of this building into a comfortable, bright, modern loft. But for phasing reasons the kitchen was left in its “natural” state. Now it was the kitchen’s turn to shine, the final chapter of an exercise in recognizing and extracting raw potential from one of Portland’s odd, unconventional buildings.

(Learn more about the loft’s additional renovation phases here and here.) While the rest of the loft’s construction was underway, owners Traci and Wynn had been making due in the kitchen’s original, funky-commercial state. Isolated from the rest of the dwelling, partially torn up with open cabinets, and shrouded in a 30-year-old drop ceiling, this kitchen had humble beginnings.

Kitchen Remodel Before | Hammer & Hand PortlandBefore photos courtesy of Risa Boyer Architecture
Loft Kitchen Remodel, Portland Oregon | Hammer & Hand

Kitchen Remodel Before | Hammer & Hand

Portland Loft Kitchen Remodel | Hammer & HandPhotography by Jeff Amram

By the light of a flickering fluorescent light bulb, Traci and Wynn dreamed about what the kitchen could be: intimate, modern, and bright. A central place for their young family to gather. They brought on architect Risa Boyer to help them translate their vision into a workable plan and invited Hammer & Hand back to provide the muscle.

Risa saw the potential hiding within. Her first order of business was opening a window in the wall dividing the kitchen from the main living space, clearing sight lines and connecting the kitchen with the rest of the dwelling.

With marching orders from Risa, Hammer & Hand set to work gutting what was left of the kitchen. H&H Project Supervisor Kevin Guinn explained, “There was a drain in the floor that came out and some old floor sinks from the commercial setting. The challenge was to convert it from a commercial kitchen to a residential one.”

A fresh start was in order. We removed the industrial drain, scraped up multiple layers of linoleum, then patched and refinished the original fir floors hiding beneath. The ancient drop ceiling tiles had to go and we framed in a new, higher ceiling and lit the room to modern standards.

Cabinets in Portland Loft Kitchen Remodel | Hammer & Hand

Benjamin Klebba from Phloem Studio created the custom walnut cabinets. “The client was looking to do something pretty minimal, so the wood became a really strong element—the cabinet above the range, the cabinets wrapping around—so we oriented the grain in that direction,” Risa says. Risa capped the cabinets with matte stainless steel countertops to show industrial’s softer side.

Loft Kitchen Remodel Before | Hammer & Hand

 

Built-In Seating in Loft Kitchen Remodel | Hammer & Hand

The team designed built-in storage and strategically placed bookshelves to protect items—namely, the family cookbook collection—from the inquisitive hands of the owners’ toddler.

The new banquette that wraps around the corner became an instant hit with the family. “The banquette has turned out to be one of the favorite parts because it gives us an intimate space to eat our daily meals together as a family,” Traci says. Risa included a brick accent wall as a nod to the clients’ experience living in New York, a factor that also influenced much of the light industrial aesthetic.

Cabinets and Countertop in Loft Kitchen Remodel | Hammer & HandOne special request from the client was a better solution for drying reused plastic bags. Tired of their janky old clip-on device, Traci tasked the design team with finding something slick. The answer was a custom installation of stainless steel pegs lining the wall.

Traci is thrilled with the results: “The bag hooks are definitely useful and genius on Risa’s part. [H&H Carpenter] Stephanie did a great job figuring out how to install them, too.”

Another special feature is lovingly referred to as “the magic corner.” This lower cabinet works like a double-jointed Lazy Susan that unfolds shelving from a deep corner, transforming what started as a storage dead zone into a graceful, maximized use of space with no bending, crouching, or blind grappling required.

With the kitchen completing the story of the loft’s new life, Wynn and Traci are content. “We still can’t believe this is our kitchen.”

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Madrona Passive House Progress & NW Green Home Tour http://hammerandhand.com/field-notes/madrona-passive-house-progress-nw-green-home-tour/ http://hammerandhand.com/field-notes/madrona-passive-house-progress-nw-green-home-tour/#comments Wed, 08 Apr 2015 22:11:37 +0000 http://hammerandhand.com/?p=6479 Today we’re excited to share a peek at our progress at Madrona Passive House and to announce that the home will be part of the NW Green Home Tour on Saturday, April 25th from 11am – 5pm. If you would like to check it out in person get tickets here! The three-level Passive House features... Read more »

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Today we’re excited to share a peek at our progress at Madrona Passive House and to announce that the home will be part of the NW Green Home Tour on Saturday, April 25th from 11am – 5pm. If you would like to check it out in person get tickets here! The three-level Passive House features sweeping views of Lake Washington and the Cascades and is currently at the beginning of the interior and exterior finishes stage.

Exterior of Madrona Passive House in Seattle, WA | Hammer & Hand

The above photo shows the home’s ROXUL mineral wool monolithic exterior insulation and 1 x 4 rainscreen. High performance windows and front door are in.

Deck in Construction at Madrona Passive House Seattle, WA | Hammer & Hand

The site’s steep slope posed unique challenges for both builder and architect. “The Passive House requirements of having an insulated foundation and the geotechnical issues all came together at the foundation,” said SHED Architecture and Design Project Manager Alex. The solution was to build an extensive piling system (check out this video for more about the pilings) with a concrete structural slab resting on top of the piles. H&H then built the Passive House enclosure on that platform.

In the photo above you can see the east side of the house and how it is built into the side of the hill. The bottom level, which will serve as the kids’ space, can be transformed into a separate ADU later on once the kids leave for college.

Interior of Madrona Passive House During Construction | Hammer & Hand

Windows are plentiful in this project, especially on the east side of the home.

“The views were a big priority,” said Alex. “The clients are very active – they spend a lot of time in the mountains. They wanted a view of the Cascades so from their second floor they could potentially see almost 180 degrees of a mountain range and almost all of Lake Washington.”

We hope you come check out the project during the NW Green Home Tour this month and we’ll be sure to share more updates as the project progresses.

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H&H to host PHIUS+ 2015 launch party for new passive building standard: March 25 http://hammerandhand.com/field-notes/hh-to-host-phius-2015-launch-party-for-new-passive-building-standard-march-25/ http://hammerandhand.com/field-notes/hh-to-host-phius-2015-launch-party-for-new-passive-building-standard-march-25/#comments Thu, 12 Mar 2015 18:30:24 +0000 http://hammerandhand.com/?p=6468 We’re excited to share the launch of PHIUS’ new North American passive building standard, PHIUS+ 2015. It will all happen here, at Seattle’s Bullitt Center, on the eve of Passive House Northwest’s annual conference, PHnw6. Please join us at the launch party, co-sponsored by PHIUS/PHAUS and Sam Hagerman (previous president of PHAUS and owner of... Read more »

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We’re excited to share the launch of PHIUS’ new North American passive building standard, PHIUS+ 2015. It will all happen here, at Seattle’s Bullitt Center, on the eve of Passive House Northwest’s annual conference, PHnw6.

Please join us at the launch party, co-sponsored by PHIUS/PHAUS and Sam Hagerman (previous president of PHAUS and owner of Hammer & Hand):

PHIUS+ 2015 Launch Party
Wednesday, March 25, 7-9pm
at The Bullitt Center’s Discovery Commons Exhibition Hall
1501 E Madison Street, Seattle
RSVP at http://bit.ly/phiusevent (Attendees will earn a CPHC CEU unit.)

The festivities will start with a beer and wine reception at 7pm, followed by an introduction to PHIUS+ 2015 by PHIUS Executive Director Katrin Klingenberg. Katrin will give a brief overview of the impetus for the new standard, as well as a capsule summary of what’s new and what’s better.
PHIUS+ 2015 provides designers and builders with a powerful building energy performance target that’s in the “sweet spot” where cost effectiveness overlaps with aggressive energy and carbon reduction. Formally known as PHIUS+ 2015 Passive Building Standard: North America, the standard is the product of nearly three years of research conducted by the PHIUS Technical Committee in partnership with Building Science Corporation under a U.S. Department of Energy Building America grant. The effort employed the National Renewable Energy Laboratory’s BEopt tool (a cost-optimizing software tool) to develop optimized design guidelines for use in North America’s wide-ranging climate zones.

This is big news for the Passive House and high performance building communities, and we’re excited that the new standard’s unveiling is happening here, on our doorstep.

Don’t miss the party!

 

Note: There is no designated parking at the Bullitt Center and there is limited street parking available in the area. We suggest carpooling or taking public transit if possible.

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How Much Does it Cost to Build a New House? http://hammerandhand.com/field-notes/how-much-does-it-cost-to-build-a-new-house/ http://hammerandhand.com/field-notes/how-much-does-it-cost-to-build-a-new-house/#comments Thu, 12 Mar 2015 16:00:30 +0000 http://hammerandhand.com/?p=6462 Building a new house is like setting out on a journey. As you prime your spirit of adventure and prepare to take the first steps, comprehending the factors that influence your destination will help you plot a clear route forward. These factors fall into three main cost categories: the property/site, the design consultants, and the... Read more »

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Building a new house is like setting out on a journey. As you prime your spirit of adventure and prepare to take the first steps, comprehending the factors that influence your destination will help you plot a clear route forward. These factors fall into three main cost categories: the property/site, the design consultants, and the builder/construction.

The Site

The place where you will live­­—be it city or country, swank zip code or homey neighborhood, vacant lot or occupied—sets the tone for the character of your project. Securing a place for your home could range in cost from $75-$500k. If you are fortunate enough to already own a site, scratch this line item off of your budget.

The Design

What your house looks like and how it functions is the product of a collaborative process between you and a design professional. The architect can help translate your vision into something tangible, assist in finding land, and coordinate with engineers, the city, and other designers. (Learn more about how we partner with architects). A ballpark estimate for architectural services is 10% of the total construction budget. Things such as engineers, permits and fees, demolition, and site development cost additional money, between 5-10% of the construction budget.

The Building

With the groundwork laid, it’s time to start bringing your home to life. Hammer & Hand is the builder. We budget, schedule, and build homes that will last. We advise on best construction practices, something that makes us unique among our homebuilder peers. Our building science and energy performance expertise ensures that your house will deliver superior comfort, health, and efficiency for you and your family. The projects we build generally cost between $250 and $400 per square foot.

Sample Home Estimate

Now let’s put it all together. Say we build a 2,500 square foot house at $300 per square foot. The base cost for the home is $600,000. Next, factor in 15% for the architect and other “soft costs,” in this case $90,000. Add the new total ($690,000) to the cost for the land/site, and the picture is complete.

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What is the Energy Performance Score (EPS) and Why Should I Get One? http://hammerandhand.com/field-notes/what-is-the-energy-performance-score-eps-and-why-should-i-get-one/ http://hammerandhand.com/field-notes/what-is-the-energy-performance-score-eps-and-why-should-i-get-one/#comments Wed, 11 Mar 2015 15:51:48 +0000 http://hammerandhand.com/?p=6398 In the past there’s been a disconnect between the green features of buildings and the valuation of those buildings by the marketplace. Homeowners have been faced with the quandary: if I invest in home performance improvements for my house but then decide to sell in a few years, will my investment be wasted (other than... Read more »

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In the past there’s been a disconnect between the green features of buildings and the valuation of those buildings by the marketplace. Homeowners have been faced with the quandary: if I invest in home performance improvements for my house but then decide to sell in a few years, will my investment be wasted (other than the good vibes of leaving behind a “greener” home)? Thankfully, that’s beginning to change and the EPS, or Energy Performance Score, is one reason.

It’s like a miles per gallon sticker for homes co-developed by Earth Advantage Institute and Energy Trust of Oregon. While it got its start in Portland, it’s also gaining traction in other markets and is available for both remodels and new builds.

The EPS is a measure of your home’s energy use and carbon emissions. To produce the EPS, our home performance team conducts a home performance assessment, which includes measuring the air tightness, insulation, lights, appliances, and heating and cooling systems of the home. The EPS is based on the total, estimated energy usage in millions of Btu per year. Because the EPS is the total, annual energy consumption of the home, the score tends to reward space-efficient structures. It also accounts for and rewards onsite energy generation from solar panels.

Energy Performance Score for Homes | Hammer & Hand

After completing the home performance assessment our team puts together an energy model using a software program called CakeSystems. This program generates the EPS.

“It’s a very simple model but it’s a fairly accurate representation of the home’s energy usage and associated carbon output,” said Hammer & Hand Building Energy Analyst Sean Hendryx. “I have compared actual energy usage from utility bills to the EPS model output and found the difference to be under 3%.”

The EPS provides a current state of a home’s annual energy usage and carbon output and a predicted energy usage after recommended improvements. The EPS helps homeowners to prioritize measures and relate the improvements to their home’s current energy use. The EPS report can inform decisions on how (or whether or not) to make energy improvements.

In the future, when Energy Performance Scores are (hopefully) ubiquitous, home buyers will be able to make apples-to-apples comparisons of various homes’ energy performance, aiding their purchasing decision just as vehicles’ MPG stickers do when shopping for a car. “It has recognition from people in the building industry, from people involved in energy efficiency programs, from people in the real estate market, and even from banks involved in allocating loans,” said Sean.

So home performance improvements can begin to not only make a home more efficient and comfortable, but also add quantifiable value to the home as well. This comes in handy when it’s time to put the house on the market. Homes that have undergone energy improvements are often valued higher and sell faster. A study, “Is Energy Efficiency Capitalized into Home Prices? Evidence from Three US Cities” by Resources for the Future, showed that in Portland Earth Advantage green-certified homes sell for 4 to 10 percent more than non-certified homes.

Here is an example of an Energy Performance Score (to see it larger, click here):

Energy Performance Score Example | Hammer & Hand

Interested in getting a home performance assessment done on your home? Visit our home performance services page to get started.

 

The featured image at the top of this post shows a thermal imaging camera in action during a home performance assessment.

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H2O and high performance building assemblies: how to handle rain and vapor http://hammerandhand.com/field-notes/h2o-high-performance-building-assemblies-handle-rain-vapor/ http://hammerandhand.com/field-notes/h2o-high-performance-building-assemblies-handle-rain-vapor/#comments Tue, 24 Feb 2015 17:05:09 +0000 http://hammerandhand.com/?p=6404 As we insulate structures and make them more airtight we reduce the drying capacity that comes as a byproduct of leaky building envelopes. To avoid increasing the risk of building failure we need to: Keep liquid water out of assemblies. Keep moisture-laden air out of assemblies. Ensure that water molecules can migrate out of assemblies.... Read more »

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As we insulate structures and make them more airtight we reduce the drying capacity that comes as a byproduct of leaky building envelopes. To avoid increasing the risk of building failure we need to:

  1. Keep liquid water out of assemblies.
  2. Keep moisture-laden air out of assemblies.
  3. Ensure that water molecules can migrate out of assemblies.

In the Pacific Northwest, a lot of our old wood-framed buildings are still standing because they leak a lot of air, inadvertently drying out building envelope assemblies. (These old buildings are also dried out by their big, energy-intensive HVAC systems, but that’s a topic for another day.) Here’s the classic case in our region: it’s a cold, rainy winter day, with some rain penetrating the siding layer of a house, making it wet from the outside. Inside the building it’s hot with people, plants, pets, pasta, and personal hygiene (showers). A plethora of vapor-producing point sources making the building envelope wet from the inside. In old buildings with unmanaged airflow this is usually fine. If we model these buildings with a dynamic hygrothermal tool such as WUFI, we see the moisture content of the wall assembly go up in the winter but fall back down in the summer when it dries out. It creates a nice sine wave where it never gets too wet and it always dries out.

WUFI Exterior Plywood

This simulation by Skylar Swinford shows a typical scenario in our climate with wall assembly components getting wet in winter and drying out in summer.

But as we modernize envelope assemblies to increase thermal resistance and reduce air leakage, “natural ventilation” through cracks in the walls drops tremendously. We’re reducing the flow of air to reduce energy movement. We’re reducing the airflow to reduce introduction of moisture into our assemblies. But by doing so we’re also reducing the capacity of the assembly to dry out. Now we as builders are forced to understand what we are doing, or risk water and vapor ruining our day.

The first step in creating a resilient high performance envelope assembly is to keep liquid water from penetrating the assembly. We do this with a continuous weather resistant barrier or WRB that repels liquid water but allows the diffusion of water vapor. Whether this is a membrane, a sheet good like Agepan, or a liquid applied product like Prosoco CAT5, the purpose is the same: keep rain out of the walls. The best strategy is put your WRB behind a ventilated cladding system (aka “rainscreen”) that manages bulk water and provides lots of drying airflow across that surface.

The next step is to keep moisture-laden air out of the envelope, and you do this by creating airtight assemblies with a continuous air barrier. In building science circles we say, “if you control for air you control for moisture and for heat.” That’s because air is a primary conduit for the movement of both moisture and heat. If air can’t move across the assembly then it can’t carry moisture into the assembly. On the other hand, a hole through an envelope the size of a dime under the right conditions can cause a gallon or two of water to condense inside the assembly every day. No joke. Bad thing. This is water being “captured” by the wall as it’s carried by the air leak across the assembly. It starts as vapor and turns to water inside the envelope structure where it’s not supposed to be. Bad things happen. The wrong people make money.

The third step is to ensure that water molecules can migrate out of your envelope. To understand why, we need to understand how vapor drive impacts our assemblies. At any given time, the absolute humidity, or the concentration of water molecules measured in a given amount of air, will be different inside and out. These water molecules are constantly seeking balance, with molecules in higher density wanting to travel to lower density. So, unless they encounter a vapor barrier, water molecules will travel from the high absolute humidity side of a wall, through the wall assembly, to the low absolute humidity side of a wall. No air needs to move to make this happen. It occurs at the molecular level, with individual water molecules diffusing through wall materials.

Now, in a consistently humid place like Houston the smart response to vapor drive is usually to make walls vapor open in one direction (inside to outside) and vapor closed in the other (outside to inside). Simple: keep the humidity in the air outside, outside. But here in the Northwest, indoor and outdoor absolute humidity fluctuate constantly. On rainy days you’ll have high absolute humidity outside setting up a gradient that drives water molecules into buildings. But on dry days that gradient will reverse and the drive shifts to moving water molecules outside. The smart response in our climate is to keep wall assemblies vapor open in both directions so that vapor can diffuse out of assemblies any which way – or, alternatively, ensure that there’s enough insulation outside any vapor impermeable layer to keep that surface warm enough to avoid dangerous levels of moisture.

Here’s the thing to avoid: condensation inside our assemblies. To do that we need to understand relative humidity, or the “humidity” you hear about on the weather report. As Wikipedia will tell you, it’s the ratio of absolute humidity relative to the “maximum” for that temperature. That last part is important: the warmer the air, the more water it can hold. See this chart (from Cerro Tololo Inter-American Observatory):

Dew Point graph from CTIO

So, to avoid the formation of condensation inside our wall assemblies we need to ensure that the relative humidity of air inside those assemblies doesn’t reach 100%, known as the dew point, for dangerous lengths of time. (For extra credit, look up “safe storage capacity of materials.”) Because relative humidity is a function of absolute humidity and temperature, we do this by keeping airborne vapor out of our assemblies (through airtight construction), allowing any vapor that does get in to escape (to avoid high absolute humidity), and by keeping the insides of our wall assemblies warm with a nice layer of exterior insulation (to increase the air’s capacity to keep H2O gaseous).

We’re controlling for heat, air, and moisture in our building assemblies. An excellent example and in-depth analysis of this kind of wall assembly is found in BSC’s article BSI-001, a classic by Dr. Joe. Somewhat misleadingly titled “The Perfect Wall.” But his discussion of the principles is spot on. To quote: “If you can’t keep the rain out don’t waste your time on the air. If you can’t keep the air out don’t waste your time on the vapor.”

We do that with thermal layers, airtight layers, and vapor permeable layers. Sometimes these layers are combined in one material. Click on the image below to see the excellent Materials Property Table by Building Science Corporation.

Preview of Materials Property Table by Building Science Corporation

Building an envelope assembly is like cooking a dinner. You’ve got a pile of ingredients on the counter (in this metaphor, all the building materials you can choose from) and you want to assemble it into a tasty meal. You’ve got to understand the properties of the ingredients and what they bring to the dish in terms of taste, texture, and nutritional value. The same is true with wall assemblies. We Americans eat a lot of hamburgers because you could probably just live on hamburgers. All the food groups, right? It’s not necessarily the best idea, but it gets the job done and no one dies. (At least not right away.) The same is true of 2×6 construction, siding, plywood, studs with fiberglass batt, and drywall.

But, if you want something that’s high performance and sustainable you have to look carefully at the ingredients and how they come together to produce the desired outcome.

Many lessons are learned the hard way. Ungapped, highly vapor retarded cladding systems such as EIFS were an excellent example of the application of a new technology with inadequate understanding of building science and hygrothermal performance. In many climates these systems failed catastrophically and had to be replaced. Partly due to failures like these, we saw the addition of a drainage plane behind cladding systems in building codes two code cycles ago. This is intended to serve as a way for bulk water to exit the cladding system on the wet side of the building. I assert that it’s also effective because it inadvertently allows some air behind the siding system. This moves it closer to the ventilated siding system (rainscreen) that I alluded to earlier: the holy grail of cladding as it maximizes the drying potential of the exterior surface of the envelope.

So! Know the vapor permeability of the materials you’re using. Put them in the right place. Control for air. Then understand how the envelope will dry out if it gets wet somewhere it shouldn’t.

But if you’ve got bulk water intrusion from the exterior, go straight to jail, do not pass go, and do not collect $200.

P.S. The transfer of vapors is a complex topic – even NASA screwed it up. For more check out BSI: Thermodynamics: It’s Not Rocket Science by Joseph Lstiburek

 

Top water droplets image by Shelly, found here.

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What is an HRV, how does it work, and why should I care? http://hammerandhand.com/field-notes/hrv-work-care/ http://hammerandhand.com/field-notes/hrv-work-care/#comments Thu, 12 Feb 2015 19:18:39 +0000 http://hammerandhand.com/?p=6390 WHAT IS AN HRV? An HRV, or heat recovery ventilator, is a balanced mechanical ventilation unit that captures up to 90% of thermal energy (heat or cool) from the stale air exhausted from a building and recycles it back into fresh intake air. In non-techno speak, an HRV is a a fresh air system that preserves... Read more »

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WHAT IS AN HRV?

An HRV, or heat recovery ventilator, is a balanced mechanical ventilation unit that captures up to 90% of thermal energy (heat or cool) from the stale air exhausted from a building and recycles it back into fresh intake air. In non-techno speak, an HRV is a a fresh air system that preserves indoor warmth (or cool) inside a building while providing a 24/7 supply of fresh, filtered air to building occupants. ERVs, or energy recovery ventilators, are closely related to HRVs, but also capture and recycle the humidity level of exhaust air.

Photo of a HRV | Hammer & Hand

Photo courtesy of Skylar Swinford

WHY SHOULD I CARE?

The old way of “ventilating” our buildings through random air leaks is not only inefficient and drafty, but also unhealthy. Poor indoor air quality is a chronic problem in conventionally-built structures. Because they rely on leaky walls for ventilation they depend on the weather to move air. If there’s no wind or inadequate difference between indoor and outdoor temperatures then there’s no force to drive air changes in the building. The result is stale, often unhealthy, air.

Even on those days that the weather does cooperate, the source quality of incoming air is poor when we rely on the old way of ventilating. A recent Washington State University study showed that forty percent of all indoor air in existing homes originates in crawlspaces and unconditioned basements. Trying to dilute indoor air pollutants with dirty crawlspace air doesn’t work.

Recent building code changes attempt to replace our buildings’ dependence on weather-based pressure and temperature differences with a dependence on mechanical pressure differences: a fan (in the bathroom, laundry room, or elsewhere) is required to run intermittently to either pressurize or, as is more common in the NW, depressurize the building. But this unbalanced ventilation approach still results in poor source quality, with indoor air being sucked through crawlspaces, basements, and leaks in walls. And even when “ports” are placed in windows or walls to create a hole for air movement, there’s no guarantee that the pattern of pressurization will actually draw air through them.

For these reasons, virtually every building built would benefit from a balanced, mechanical, fresh air HRV or ERV system – and the more airtight the building, the better that system will perform. We know where incoming air is coming from: a clean, filtered intake leading directly through the HRV or ERV, delivering healthy fresh air, comfortable interior temperatures, and a smaller carbon footprint.

HOW DO HRVs WORK?

Fresh intake air is (1) drawn in from outside, (2) passes through the HRV’s (or ERV’s) heat exchanger where up to 90% of thermal energy from exhaust air is transferred into the incoming air, (3) if necessary, passes through a heating or cooling unit to move the air temperature up or down the remaining few degrees to the desired level, and (4) is delivered to bedrooms and living areas. Exhaust air is (1) drawn from kitchen and bathrooms where odors and pollutants collect, (2) passes through the heat exchanger where it shares its thermal energy with intake air, and (3) is exhausted to the outside.

HRV Diagram

Diagram courtesy of Skylar Swinford

The two air streams – fresh intake air and stale exhaust air – never mix. In the highly efficient units we use, the two streams pass through a honeycomb-like structure of thin-walled passages inside the heat exchanger that provide a very large surface area for the transfer of energy between adjacent intake and exhaust air streams.

HRV | Hammer & Hand

Image courtesy of Paul Wärmerückgewinnung GmbH

BUT WHAT IF THE POWER GOES OUT?

To be clear, it’s not a big deal if the HRV cuts out during a power outage, as even the most “airtight” buildings are far from hermetically sealed. No one’s going to suffocate! Granted, it might get a little stuffy, though. The solution? Crack a window or two until power is restored. The good news is that the passive qualities of high performance buildings extend the “open window season” anyway, so you’ll still be more comfortable during that power outage than your neighbors in their old drafty buildings.

P.S.
Check out these videos about the HRV at Karuna House:

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http://hammerandhand.com/field-notes/hrv-work-care/feed/ 0 How an HRV (Heat Recovery Ventilator) Works | Hammer & Hand WHAT IS AN HRV? An HRV, or heat recovery ventilator, is a balanced mechanical ventilation unit that captures up to 90% of thermal energy (heat or cool) from the stale air exhausted from a building and recycles it back into fresh intake air. In non-techno speak, an HRV is a a fresh air system that p hrv-pic hrv-diagram hrv-heat-exchanger
Airtightness at Madrona Passive House? Easy peasy. http://hammerandhand.com/field-notes/airtightness-madrona-passive-house-easy-peasy/ http://hammerandhand.com/field-notes/airtightness-madrona-passive-house-easy-peasy/#comments Sat, 07 Feb 2015 00:09:41 +0000 http://hammerandhand.com/?p=6351 One of three performance metrics for Passive House certification is air tightness of the building envelope (the other two are heating/cooling load and primary energy demand). After months of construction it was time yesterday to test the air tightness of our Madrona Passive House project. We’re excited to say that the results from our blower... Read more »

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One of three performance metrics for Passive House certification is air tightness of the building envelope (the other two are heating/cooling load and primary energy demand). After months of construction it was time yesterday to test the air tightness of our Madrona Passive House project.

We’re excited to say that the results from our blower door test came in at .32ACH50! That’s almost 50% better than the air tightness standard (.60ACH50). The structure of the building has more complexities than a simple design, which makes meeting the air tightness standard a bit more challenging. That’s why we’re particularly excited to have such a successful blower door test.

Blower Door Test at Madrona Passive House in Seattle | Hammer & Hand

Left: Passive House colleague Brian Cowan is immersed in the cloud of theatrical smoke used to locate air movement. Right: The gauge showing building pressure at 50.5 pascals and air flow at 153 cubic feet per minute.

Below: Front entry door showing no air leaks during the test.

Door at Madrona Passive House | Hammer & Hand Seattle

Now that we’ve completed this test we can move ahead with covering up our building shell. This will involve installation of the Roxul ComfortBoard IS and ventilated rain screen battens. This will quickly be followed by the Forest Stewardship Council® certified cedar siding.

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Hammer & Hand Seattle Team Recruiting Event http://hammerandhand.com/field-notes/hammer-hand-seattle-team-recruiting-event/ http://hammerandhand.com/field-notes/hammer-hand-seattle-team-recruiting-event/#comments Mon, 02 Feb 2015 16:41:48 +0000 http://hammerandhand.com/?p=6266 Calling all experienced carpenters! Hammer & Hand, a leader in high performance building, is looking to add members to our Seattle team. Our Seattle team is hosting a recruiting event at our office in the Bullitt Center Tuesday, February 24th from 5-6:30pm. Anyone interested in learning more about Hammer & Hand and furthering their career... Read more »

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Calling all experienced carpenters! Hammer & Hand, a leader in high performance building, is looking to add members to our Seattle team.

Our Seattle team is hosting a recruiting event at our office in the Bullitt Center Tuesday, February 24th from 5-6:30pm. Anyone interested in learning more about Hammer & Hand and furthering their career as a lead carpenter or project supervisor is welcome to attend. Co-owner Sam Hagerman will be there to discuss the history and future of the company. Attendees will also have the opportunity to talk with H&H project supervisors and HR professionals.

H&H is growing in Seattle, with a number of exciting projects on the horizon. We are looking for skilled men and women to add to the team. View open positions here.

Event Details:

Tuesday, February 24th, 2015
5:00 – 6:30pm
Bullitt Center
1501 E Madison St. Suite 250
Seattle, WA 98122

Instructions:

There is no off-street parking at the Bullitt Center, so arrive in time to find street parking. Use the call box (look for “Hammer & Hand”) at the Madison St. entrance to be buzzed into the building. The office is through the first door and to your right (across from the living wall).

Please RSVP to this free event here:

 

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