What Happens to House? A Cautionary Tale November 03 2015, 0 Comments
All Quiet on the Eastern Coast November 02 2015, 0 Comments
What have we been doing for the past six months?
We've been busy.
Too busy. Insanely busy. To busy to even write a blog post. Nose to the grindstone, head down, fingers to the bone.
Meeting monster deadlines!!!
Developing new courses!!!
And we're nearly ready to let 'em loose on y'all.
Solterre June 10 2015, 0 Comments
Here's an article that was just published in Home Energy Magazine (July/August 2015). To read the whole article, you must have an online subscription. It's about a very cool project that our colleagues Jennifer Corson and Keith Robertson at Solterre Design designed and built to test drive a range of assemblies, design principles and mechanical system options for very low-energy, off-grid housing in Lunenburg County. The LEED Platinum, Passive House certified final product is a success on all fronts. Check out Solterre's impressive body of work.
Jennifer and Keith (and their two kids) also just returned from a 3-month stay in Ghana, where they worked on a rammed earth library. Very cool story, and very cool people. Here's a local news story about their Ghana adventures.
Learning Platform Needs - what do you want? May 06 2015, 0 Comments
We're expanding our online learning services to include:
- Learning management system (LMS) implementation and management
- Integration of e-commerce
- Development of new content and conversion of face-to-face content for online delivery
To make sure this fits with your needs, we've developed a short, anonymous online survey. Please take 5 minutes (or less!) to fill it out now.
We'll summarize the results into a new white paper that focuses on ways to develop online/blended-learning programs. To get the summary and the white paper, send an email to customerservice.
Complete the Survey ►
Sping Training vs. NOLA May 05 2015, 0 Comments
Spring Training won this year. Last year, I went to ACI National in Detroit (I know, I know, Detroit yes, NOLA no?). This year, I went to Spring Training with the Canadian Building Science crew outside Huntsville, ON (I know, I know rural Ontario vs. NOLA in Spring? What?). The fact of the matter being I have not had chance to connect with my people for years. And there we were, 120 of the most intense B.S. wonks, nerds, and geeks. Hosted by Tex McLeod, Gord Cooke, and John Straube, with pithy interjections from Oliver Drerup, the mainly Ontario crowd was infiltrated by a small East Coast contingent, as well as some folks from the West. It was a great two and a half days, jammed with good sessions and no opportunity to get away from the crowd. The first day's sessions were focussed on Net Zero Energy homes, with Sam Rashkin doing the honours as keynote speaker, and a panel of builders from across the country talking about their experience in building and selling NZE homes. Second day's sessions were all about tall wood buildings -- not so much relevance to what we do at BHE or through Bfreehomes, but still interesting and definitely cutting edge stuff. I mean, 10 and 18 storey wood structures? Come on -- that's impressive.
Gail Lawlor (Energy Matters) and I did a quick presentation on BPI Canada -- a site-based quality assurance program that we are aiming to launch after several years of it being a Good Idea. More on that project and the Spring Training Sessions in upcoming articles.
Still, I'll be missing all my US cronies and pals who ramp up ACI -- or HPC as it is now known -- in NOLA today.
Shout out to the Zymurgologists on both sides of the border.
Bonus Points for Blended Learning March 23 2015, 0 Comments
There's a lot of times when face-to-face training is the only thing that will do. Especially in the home performance industry: hands-on is the only way you can really learn to identify and diagnose energy-sucking and moisture-growing situations in a house. But to understand what you need to identify and diagnose, you need to have a good grasp of background concepts and physics, and how they impact the performance of the house.
Everything that happens in a house is caused by things you can't see and you can't hold: heat flow, air flow, moisture flow, neutral pressure plane. It can be a challenge to teach these concepts, especially to folks who are hands-on learners. Which, not surprisingly, is a high percentage of people who work with their hands.
Blended learning has been a staple of this industry's training: classroom time is mixed with field time in almost all programs. But classroom time is very expensive, to both the provider and the participant. And participants come to a course with a wide range of experience and existing understanding, not to mention differences in learning styles. Adding an online component to that blended learning package can help reduce stress in several ways.
Check out our white paper on blended learning here.
OK, so who should take Building Science Basics? March 10 2015, 0 Comments
If you work in home construction and renovation, you know about energy efficiency measures. But do you really know it?
If you’re trying to figure out if you need this course or not, take a shot at answering these questions:
What happens to the neutral pressure plane when you air seal the basement headers but don’t do anything else to the house? And why should you care?
What about combustion spillage? How do you tell when it’s an issue in a house, and how do you solve it?
What's important about knowing where the dewpoint is?
If you don't know how to answer them, then you need some training.
It’s costly to take courses.
If you take a day off work, it’ll cost you.
If you register for a day-long workshop, it’ll cost you.
If you have to travel to get that training, it’ll cost you.
And face it, if you are out somewhere, you’re likely to buy lunch if it’s not supplied, and then after, maybe you and your workshop compatriots are off for a beer. It’ll cost you.
And you’ll be stuck in a classroom. All. Day.
Online training doesn’t take the place of hands-on learning. It builds on your experience so that you can do a better job.
So check BHE training out. There’s still a little pain, because we need to make some money and you need to give up some time. But it’s not so bad. Promise.
We give you the animated goods on house-as-a-system, indoor air quality and ventilation requirements, and you learn at your own pace in your sweats.
In a marathon 3 to 4 hour session or in 10 to 15 minute chunks. Totally digestible while snacking.
This is basic training for any energy efficient building program or certification, so you’ll have a good solid start on any future training you do. It's also good for continuing education units (ask us about this, some of our resellers have better regional CEU options than we do).
In the end, you pass a test (no trick questions, all multiple choice or T/F answers) and we give you a certificate of knowledge, which you can use as a proof of learning, that you understand how you’re affecting a house when you carry out air sealing work or add insulation.
And then you can treat yourself to lunch and that beer. ‘Cause you earned it, buckaroo.
Training Partners Program Takes Off March 09 2015, 0 Comments
We’re very excited about the interest in our Training Partner program that we launched in January 2015!
We’re now supplying online training in building science to two very different organizations: a non-profit green building certification organization in Michigan and a home performance training center in California. We’re also talking with face-to-face trainers who supply training to remote communities with no internet connection (delivered via iPad and local LAN), and several more regional trainers who want to streamline their offering. They all have very different training programs and approaches, but we’re mighty flexible.
GreenHome Institute, based in Michigan, was formerly The Alliance for Environmental Sustainability (AES). GHI’s mission is to empower people to make healthier and more sustainable choices in renovation and construction. Building Science Basics is now the starting point for the GreenHome Professional certification, which gives people a way to further distinguish themselves as a residential green building experts.
The comments from the first person through the training with GHI gave us serious permagrin:
“I have passed the Blue House Energy course, that was really cool. I think everyone should go through that training. More importantly I would like to bring my employee, that way EVERY SINGLE person in my company will be qualified.”
BHE courses, when taken through GHI, are eligible for continuing education units (CEU) from organizations including: BPI, GBCI, & AIA (HSW). NARI Green is expected soon, and we’re working on NATE credits too.
Building Performance Center Inc. (BPCi), is one of the premier training resources for the clean energy workforce in California, offering a wide range of industry certifications and credentials. The BPCi runs a full-service training, test and mentoring facility that offers a real-house environment for hands-on practice to build confidence and skills ability, gain experience in diagnostics, testing, and remediation, and prepare for examination.
This is our first partnership with a training organization that blends online, classroom, hands-on labs, and field house learning and testing. Starting in March 2015, BHE online training is the first component of BPCi’s BPI Building Analyst Training and HERS rater training, underpinning the solid classroom training provided by BPCi’s seasoned instructors, Andy Wahl and Laura Seidman.
We’re finalizing the range of CEUs that will be offered through BPCi, because California’s special that way, you know.
Having our courses as the starting point of online training for the GreenHome certification programs, and as the foundation for BPCi’s face-to-face training fulfills one of our top goals: improving the capacity of our industry by collaborating with other training organizations.
Proper installation technique for proper batt insulation February 20 2015, 0 Comments
Oh, how I yearn for RESNET Grade I installations...here's how to get 'em.
Drainwater Heat Recovery Units & Water Efficiency February 16 2015, 0 Comments
Hot water distribution efficiency is now included in HERS ratings, under an amendment to ANSI/RESNET Standard 301-2014. This is a Good Thing. To date, all of our efforts to represent, and then minimize, hot water usage have been skewed by distribution systems (ie, by the vagaries of plumbing). According to David Butler (Optimal Building Systems LLC), the amendment not only incorporates distribution efficiency metrics, but also makes signification revisions to basic DHW efficiency calculations (consumption and waste rates, inlet/mains water temperature). Here's the amendment in full.
In some discussion groups, there's been a few posts about drainwater heat recovery (DWHR) units. I like these beasties. They are passive collectors of waste heat from the drainwater from showers. With the right plumbing set up, they can be very effective. They became less attractive in the last few years with the price of copper going up, but when operating costs don't go down (and where inexpensive natural gas isn't the go-to source for hot water), the case can still be made for using DWHR units. This is especially true in new houses in cold climates, where the average inlet or mains water temperature hovers around 44 - 70°F (with most of the year staying on the nasty cold side of that range).
I wrote up a Research Highlight on DWHR units for Canada Mortgage and Housing Corp (CMHC) a few years ago based on two studies run in the Canadian Construction Test Houses in Ottawa. It's based on cold-climate housing and cold water feeds (2005 study range 49-67°F, 2006 study regulated at 46°F), so not applicable further south, but interesting read on the performance levels of the various configurations. Here's the pdf link.
And here's a groovy little calculator based on the findings from those studies (and others). Dial in the water usage, temp settings, plumbing configurations, fuel type and price, DWHR type and size. Again, only in Canada, I'm afraid ;-).
Add to this calculator some ways of achieving efficiency in hot water distribution (ie, best practices for plumbing runs in general, requiring DWHR units to be tied into one vertical drain for all the showers in the house, take toilets and other all-cold waste water producers off that shower drain) and you may have a strong case for improved water efficiency.
The problem: DWHR savings are very hard to map. In part, because occupant behavior changes. When there is more hot water, more hot water gets used. I've not seen a conclusive behavioral study, but have lots of anecdotal evidence. Can't waste that recovered hot water! Just like with solar thermal -- it looks like I get whopping savings out of my 2 panel system (especially in the summer), but I also know we use way more hot water in the summer and should seasons now that we have the solar thermal system because otherwise we're wasting all that lovely 'free' heat. It shouldn't come as a particular surprise, give then number of articles and papers documenting bigger footprint houses fitted with any number of gadgets and electronics leading to occupant behavior that trumps any energy savings improvements in the building envelope and mechanical systems.
BHE online training as prep to classroom training! February 16 2015, 0 Comments
We're so very pleased to announce our partnership with Building Performance Center Inc, in Folsom, CA. Our online training is the preparatory course for classroom training for Building Analyst training (BPI Certification). BPCi has a fantastic facility, the Field Training and Test House -- trainees are guaranteed lots of hands-on time with diagnostic equipment, in classes led by instructors who really know their stuff.
This is what we envisioned, working with great partners to amplify the benefits of hands-on training. BHE Building Science Basics is a benchmarking tool as well as an educational product. The online course makes sure that everyone coming into classroom or field training has a basic understanding of building science. An customizable exit survey allows the trainer to get a handle on the knowledge base of their trainees before class room or field time, so that the trainer can focus on the needs of the group and, ultimately, offer them a tailored training program.
If you are interested in a blended learning program like this, please give us a shout. We're looking for more regional partners.
Blown-in vs. Batt: what are the realities? February 15 2015, 0 Comments
From the newsletter of Northwest Energy Star (Q32014):
Bibs vs. batts: Who ya got?
Recently, some blown fiberglass products were shown to offer the same resistance to airflow when blown to a density of 2.3lbs/cubic foot as cellulose does at 4lbs/cubic foot. Energy Trust of Oregon was intrigued by these lab results and set out to see if they translated to the real world of production builders.
To find out, Energy Trust conducted a study in 2013 of 40 new homes comparing the airtightness of homes using batt insulation in the walls with homes using the blown-in wall system. On average, the blown-in wall system proved to be 1 ACH50 lower, resulting in a tighter home. Additionally, the houses with the blown-in wall system all had a higher average R-value (R-23) than the homes with batted walls (R-21). While lower infiltration and higher wall R-values are important, the blown-in systems also resulted in lower levels of inside noise. Interestingly enough, this was the feature homebuyers commented on the most, which is ultimately what convinced many builders to adopt the technique for all their new homes. To quote one builder: “I can sell quiet.”
GreenStar: A Certification Program for Remodelers and Renovators February 05 2015, 0 Comments
There are some outstanding ‘green’ certification or standard programs for new home builders, not so many for remodeler and renovators. Our biz partner, GreenHome Institute offers one that is used in seven mid-Western states, called GreenStar (it’s good for certifying new homes too, BTW).
There’s a lot to cover in a certification program, and this one does a good job of it. The program covers the five pillars of green: energy, health, water, materials and site/community. Recent additions to the program include checklists for accessibility and Zero Energy. There’s an in-depth checklist, a manual and a specifications tool, all of which have been well-thought out and are very thorough.
We’re very pleased to be working with GreenHome Institute, an organization that has members and leadership with the vision and passion to create a home certification program, and match it up with a training program for green renovation professionals.
Cindy Ojczyk (o-check), co-developer of GreenStar, well-established sustainable designer and serious green remodeling blogger, will be running two qualification training programs for GreenStar in Minneapolis. You come away with the checklist, manual and specification tool as well as the basic qualifications you need to become a GreenHome Institute Associate. The workshop also qualifies for continuing education units from GBCI, AIA (HSW), NARI Green and NGBS.
Here are the links to the training dates:
Who should attend?
- Residential design and construction professionals in the new and existing homes market.
- DYI Homeowner’s seeking resources and managing their own projects.
- Real estate professionals looking to under the value of GreenHomes.
- Policy makers & code officials.
- Affordable housing & multi family developers.
Update from Cindy: In last week's GreenStar training (Jan 31) workshop, every single person in the class was there because customers and clients were asking for green. Attendees include an electrician, appliance retailer, interior designer, and a very large design/build/remodel firm that sent 9 people to training. So get on board, y'all!
Introducing our new partner: Green Home Institute January 23 2015, 0 Comments
Our news of the week: we've partnered with GreenHome Institute (GHI) out of Grand Rapids, MI, to offer Building Science Basics to more folks in the industry. Through GHI, Building Science Basics is eligible for more continuing education credits:
10 CE hours for AIA-HSW
10 CE hours for USGBC
4.5 CEUs for BPI
GHI (formerly known as Alliance for Environmental Sustainability) is led by Brett Little, who was recognized in 2014 by Home Energy Magazine as one of the 'Top 30 under 30' to watch in the industry. GHI offers a training program that results in the GreenHome Associate designation. Once you have your GreenHome Associate designation under your belt, you become a GreenHome Professional by completing a certified green project. GHI also has a certification program for green, energy efficient remodeling projects called GreenStar Homes (more on that in a different article).
There are three components to the GreenHome Associate training, all online:
Building Science Basics (that's us!)
- House as a System
- Indoor Air Quality
- Ventilation and Combustion Spillage
- Air Sealing Fundamentals (bonus module!)
Green Building: Principles and Practices in Residential Construction (online reading)
- Outdoor Living Spaces
- Interior Finishes.
- Renewable Energy
- GreenHome Certification & Labels 101
- The Most Accessible Home in Country – An Overview
- Journey to LEED Platinum and Almost Passive House
- America’s Oldest Net Zero Home Remodel – How did they do it?
- Natural Building in Cold & Wet Climates
The Path to Net Zero/Zero Net Energy (Ready) January 19 2015, 0 Comments
Here's a presentation based on our work with Natural Resources Canada on The Path to Net Zero Energy housing. The study challenge was to look at incremental reductions in energy use and flag where the envelope improvements ended and the mechanical system design started. There was a lot of number crunching. A lot. (EnerGuide Ratings are like HERS ratings, but are based on a 0-100 scale for energy use, with a NZE house being 100 or more).
Slide #5 is the key: looking at the end use patterns and changing the proportions means that as the space heating load goes down, the water heating load drives more mechanical system choices.
Four case studies are included.
Question: How to stop pressure-driven water leakage at windows January 19 2015, 0 Comments
Reblog: What's Reasonable vs. What's Heroic January 19 2015, 0 Comments
Ann Edminster, M.Arch, LEED AP (a long time colleague) is a recognized international expert on green-home design and a principal developer of the LEED for Homes rating system. Here’s a story about Ann’s house in Pacifica, California, in interview format with Jim Gunshinian from Home Energy Magazine. This Q&A originally appeared in Home Energy magazine's January/February 2015 issue. You can view the full article on www.homeenergy.org.
Jim Gunshinan: Ann, Terry Nordbye, a Home Energy author, is consulting on an attic retrofit at your home.
Ann Edminster: I’ve lived in this house for 28 years, and it has been upgraded many times; it started life as a 1947 Sears Roebuck kit. It was pretty simple before I got my hands on it. Not so simple now.
I’ve always wanted to do what’s reasonable here, but not what’s heroic. My attic had a light dusting of something the color of dirt all over it—maybe ancient cellulose? Bits of fiberglass dotted the floor, looking like cake decorations. I’ve done just about everything else in the way of reasonable upgrades, so reinsulating the attic was just a project waiting to happen—waiting for the right people and the right insulation.
JG: How’s the project going so far?
AE: Terry’s been providing guidance for Don Kingery, a general contractor recommended to me by Andy Wahl, a home performance consultant and trainer who has also helped out on the project. I am an advisor for Havelock Wool, a manufacturer of New Zealand wool insulation, and they agreed to supply the insulation for the attic—finally, a product I can get excited about! But before we could lay down the insulation, we had to clear out the attic really well and air seal. We weren’t sure we could lay the wool over the existing knob-and-tube wiring, so we updated the electrical first.
The roof is low slope, about 3:12. It is hipped on two sides. There are skylight wells, a second-story addition, and a parapet wall. Part of the original roof had been chopped to create space for a deck. Like I said, not simple. We decided to take out the eave vents to create space for more insulation and allow for better air sealing, and added a new side vent through the parapet wall to make up for it and to provide access to the attic. This also enabled us to seal off the old ceiling hatch (another air leakage point).
Terry is an air sealing specialist. After the guys vacuumed and swept, Terry and the crew used gun foam and tape to fill in and cover any holes bigger than 1/8 inch or so. That’s where we’re at now.
JG: What’s next?
AE: Terry has a relationship with Western Colloid, and they want to try out a new elastomeric product Terry calls Product X. Terry has found that the gun foam doesn’t hold up so well over time, so to completely seal the attic, Terry is going to spray all over with the elastomeric product. It will take some time to dry, and then next week we’ll install the wool insulation.
This small attic project has turned into a major attic experiment! Terry will have lots of before-and-after blower door numbers to share when we’re done. We’re all quite excited about it. I call those of us who play with our houses this way the Let’s Try It at Home Club. There’s always another project around the corner. We may install a second solar array next. Stay tuned!
SH: I'm looking forward to hearing more about Product X!
Our Training just got more affordable January 13 2015, 0 Comments
Valuing the role of the appraiser in home performance January 12 2015, 8 Comments
Here's something near and dear to the heart of anyone involved in the home performance industry: how to make energy efficiency sexy, appealing, and properly valued. When you're up to your eyebrows in insulation and you know that you are adding significant value to a house, it's sometimes hard to perceive why the value of the good work and long-term benefits that you are creating for homeowners seems to disappear with the installation of the drywall over the insulation and air barrier. Homeowners who are committed to the long haul are the ones who recognize the value -- they see it every month in their energy bills, and feel the difference in their overall comfort level.
Then there's a whole raft of other people who don't recognize the value, or have no way to quantify the value of energy efficiency work so that it can be included in the overall value. And it just so happens that that raft is tied to the financing and sales processes. And the person who has the tiller, to stretch the Maritime metaphor just a little bit more, is the appraiser: the objective third party who assesses the home determines how each feature contributes to the overall value of the house.
If an appraiser can't to evaluate energy efficiency measures because they don't have a way to navigate through the waters (ok, yes, I am liking the metaphor way too much), they are certainly not going point the raft into unknown territory. Both the US and Canadian Appraisal Institutes recognize that energy efficiency measures can add to value, but how the appraiser determines that value is at issue.
In Canada, properties are valued in three ways: the income approach, the direct comparison approach and the cost approach. The income approach is based on the value of the revenue generated by a rental or lease property at it's highest and best use. The direct comparison is based on what it would cost to buy another existing and equivalent property, based on recent selling prices and current listings in the immediate area. The cost approach is based on how much it would cost to build an identical building at current prices and estimated land value, less accumulated depreciation.
Regardless of the how the valuation is carried out, the appraiser cannot determine value of a component or feature if it is not included in the sales sheet. For example, if a deep energy retrofit on an older home or a solar thermal or a PV system or if the fact that a house is Net Zero Energy ready, are not considered sales features, they can not be included in the valuation. An appraiser coming across one of these unusual sales features for the first time might scratch their head. With nothing to compare it to in a region or a neighbourhood, how do you determine what it's worth?
Who needs to be involved? Homeowners who have houses with these features, builders who are offering new construction packages with these features, realtors who are selling houses with these features, buyers (and their realtors) who are looking for houses with these features.
There are already some tools, methods, and programs out there for green appraisals. I can't walk you through that process -- it feels a little like alchemy to me. And this article from Home Energy Pros in the spring of 2014 lays out the groundwork for how to start and makes two outstanding points.
What are homeowners, builders, and realtors all going to be required to provide for appraisal? Documentation. Performance testing results. Installation specifications. Possibly technical specifications.
Who's going to determine the value? The right appraiser. One who has some credentials and an industry-acceptable format with which they can catalogue home performance features. Any appraiser, regardless how experienced they are, will have difficulty parsing out the important info from a boatload of documentation on systems, products, and upgrades that they are unfamiliar with. consistent, standardized documentation across the board is going to help...
Once new features are on several sales sheets and transactions have been closed, they have become part of the product, and can then be assigned value that is pertinent to the local market. And then they're valuable. And marketable. Think better closing prices, shorter on-market times, happier clients all round: sellers get more money, buyers get more value. Win-win.
Floats my boat.
QUICK PRIMER: Air Barrier v. Vapour Barrier January 05 2015, 0 Comments
An air barrier stops air from moving in or out of the conditioned space, effectively blocking the air pressure differences that drive the stack and wind effects. Air barriers can be in place anywhere in the building envelope, and there can be more than one air barrier. Air barriers can be created from a wide range of materials: polyethylene sheeting, house wrap, self-adhered membranes, boardstock, board insulation, spray polyurethane foam, poured concrete, metal, glass, and a host of other materials.
A vapour barrier stops water vapour from diffusing through materials -- and so there is a more descriptive name: vapour diffusion retarder. In cold climates like Canada’s, the vapour barrier should be on the inside of the insulation. In hot climates, it should be installed on the outside of the insulation. In both cases, the vapour barrier prevents warm, humid air from leaving its moisture behind as it meets a cool surface, regardless of the direction it is moving.
Things get complicated in energy efficient construction, because a material can be an air barrier, a vapour barrier, a weather barrier, an insulator or any combination of those four functions.
The satisfaction of saving a basement from itself... December 30 2014, 0 Comments
The original basement: rubble, damaged, water issues at the slab, scrabble, rock and broken thin slab floor, insulation stuffed in window wells with cracked glazing in the frames, daylight visible between window/wall, cellar door/wall, joists/top of wall, and even peeking through between some of the rubble. Two monster oil-fired boilers and two uninsulated electric water heaters. Oh, and 6'5 clear height.
Happily, this rubble basement was very dry. No problems with water penetration through the walls once the daylight between the rubble was parged over, lovely dry joists high above the outside grade. The decision for more living space: Dig it out! If the basement had not been so lovely and dry, there's no way this would have been the right solution. Spray foam in wet basements gives you ten kinds of yuck.
Finished product: 2 bedroom + bath plus living space with 8 foot ceilings, R40 walls (closed cell foam against rubble, standoff 2x4 wall on gaskets, cavity filled with rockwool), R20 under the slab, radiant infloor supplied by solar thermal/propane.
QUICK PRIMER: Drainscreens vs. Rainscreens December 22 2014, 0 Comments
A drainscreen is a self-draining material (often a proprietary mesh or netting) between between stucco or cement cladding and the drainage plane/waterproof layer, especially common with insulation finish system (EIFS) wall assembly (which is often also the exterior air barrier in EIFS assemblies). Drainage paths allow the water to get out of the wall. Old-school stucco walls rely on the small gaps between the building paper and the lath for their drain screens. In the illustration, the black mesh layer is the drainscreen
A rainscreen is most often a non-proprietary detail that uses strapping or furring to create an air space between the sheathing and the siding in a wall assembly, allowing the moisture on the exterior side of the sheathing (the drainage plane) to both drain and evaporate out of the wall cavity. The air space is vented, so there is equal pressure on the front and back of the siding, reducing the amount of water driven into the siding.
- Both create a capillary break between the sheathing and the cladding/siding.
- Both require very careful attention to the drainage plane, especially flashing and taping at openings and connections between different assemblies and building components.
QUICK PRIMER: Thermal Bridging, Dew Points, and Exterior Insulation/Air Barriers December 17 2014, 0 Comments
Insulated sheathing materials can provide an air barrier along with a thermal barrier, and solve the biggest challenges of thermal bridging. The challenge of using insulating sheathing as an air barrier is to ensure that the R-value of the sheathing is high enough that it moves the dew point outside the cavity of the wall. The layer of foam makes it more difficult for the wall to dry to the exterior, so it must be thick enough to warm the wall cavity enough so that moisture doesn't accumulate. And then, you need to think of how the wall system is going to dry to the interior - it is recommended that low-permeance layers (polyethylene, closed cell foam) are avoided on the interior. This is a challenge in jurisdictions that require vapour barriers, and where the building code vapour barrier requirements mean you're stuck with polyethylene, instead of a Class III vapour barrier such as latex paint or other options.
This 2011 article from Green Building Advisor's Q&A Spotlight gives a good summary of a forum thread on a retrofit that included exterior insulation. It also points to a blog entry by Martin Holladay on minimum thicknesses for rigid foam sheathing.
Know the issues around Solar Ready in your area December 08 2014, 0 Comments
Solar ready sounds pretty groovy.
But what does it mean?
There is no uniform definition.
At one level, it applies to minor changes in the design and construction of individual houses or buildings to ‘rough-in’ the necessary elements to accommodate a future photovoltaic (PV) or solar hot water (SHW) system. At another level, it applies to right-to-light legislation, zoning, code compliance and municipal policies relating to solar. Solar ready ‘rough in’ guidelines exist in the form of voluntary ‘green building’ programs for builders and developers to feature in their new house offerings, as one item on a picklist for energy efficient or sustainable house rating systems, and as a mandatory item for code-compliance in local building codes and ordinances. So you could be dealing with several different levels or scopes when you offer Solar Ready to your clients. Here's what you need to look for in your region:
Solar Ready Guidelines – guidelines published by national agencies in Canada and the US, used by builders and referenced by building energy standard programs.
Solar Ready Programs – optional/voluntary and mandatory programs run by municipalities. These programs build on the guidelines noted above and often are part of a broader ‘solar readiness’ initiative.
Solar Ready Regulations and Legislation – bylaws, ordinances, regulations or code-compliance requirements for solar ready in new construction.
Solar Readiness – the broader issues related to successful solar policy and planning initiatives.
Solar Ready Guidelines
In their most basic form, Solar Ready guidelines address:
- adequate roof area
- appropriate orientation to the sun
- minimal obstruction and shading
- a direct route for conduit or piping from the roof to the utlity or mechanical area
- enough room to install the balance of system for photovoltaics and/or solar hot water
- site planning
- building form and massing
- space planning
- mounting strategies
- roof pitch
Many details go into optimizing a building for solar at the planning stage, and then there are solar readiness guidelines, which have been developed to optimize larger solar initiatives at the municipal or regional scale and to address broader issues related to municipal ordinances and zoning issues.
In Canada, Solar Ready Guidelines for both PV and solar thermal were developed by Natural Resources Canada in partnership with the Canadian Solar Industries Association. In the US, guidelines have been developed under the wing of the National Renewable Energy Laboratory (NREL). The EPA's Renewable Energy Ready Homes (RERH) program is broken out into two distinct sets of specifications and checklists, one for PV and the other for SHW.
While most municipal and regional programs refer to the guidelines developed by NRCan and NREL, most of the building programs in the US, such as Energy Star for New Homes and the DoE Challenge Home Program, reference the EPA developed Renewable Energy Ready Home guidelines. The Earth Advantage Net Zero Ready Certification and LEED for Houses Solar Ready credit reference the RERH guidelines as well.
Along with NRCan’s Solar Ready Guidelines, a Solar Ready Truss design procedure was developed by the Truss Plate Institute of Canada (TPIC) in 2012 to deal with concerns about additional loads associated with solar collectors. Technical bulletin #7 establishes compliance with the National Building Code of Canada; the CSA O86, Engineering design in wood and TPIC design procedures.
Model Construction Specifications
The guidelines developed for the Twin Cities Solar Ready Requirements, while based on the NREL guidelines, have become a well-referenced resource for solar ready initiatives. The Solar Ready Construction Specifications, documents the solar ready system so it can easily be incorporated during the construction process. The guidelines and specifications address two specific building types: urban new single family and duplex houses with pitched roofs; and 1 to 4 storey flat roof structures (multi-family residential, commercial/office or mixed use buildings).
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