Practical Eco

Powered Attic Ventillation? Contentious subject.

On my walk around the neighborhood yesterday I saw the biggest roof mounted attive ventillator that I've ever seen - twice as big as the one pictured.  So it's got me thinking about the issue of attic ventillation. 

The sales positioning for these fans is that by ventillating your attic you remove the heat and save money on your air conditioning.  But I've read a respected view from Advanced Energy that refutes this claim.  See the article on Advanced Energy's site here.  They say that since almost all of the heat gain is through radiation that ventillation will do little or nothing to improve that.

I consider Advanced Energy to be an authority on matters like this. They do real field research and testing. The houses they tested were all being depressurised to some extent - that's what mainly causes the risk of flame roll out. And you really want positive pressure in your house, at least here in the South. Positive pressure keeps the house from sucking in impurities.  The attic can also pull your cool air up through the cieling and into the outdoors. So it's very important that a house with powered attic ventillation is thoroughly sealed between the conditioned space and the attic space.

On the other hand, speaking to builders I hear the view that you've got to get rid of the heat that builds up in the attic somehow. Proper ventillation is the only way to do that. One builder tells me that in his own attic he has experienced cooler temperatures since installing a powered ventillator.  Also I found a very detailed report here from the Florida Solar Energy Center that explores the issue well and comes down in favor of powered ventillation.

It's obviously a complex issue with no simple answers.  If building from scratch or if you can afford it, I'd seriously consider spray-foam insulation and sealing the attic - especially if your ducts run in the attic space. For an existing house with ducts in the crawl space, I'd first make sure the attic floor was well sealed from the cieling below so that air isn't exchanged. Then I'd insulate well. Then I'd possibly consider a powered attic ventillation system last. 

HBA Green Building Tour - May 3-4

The Home Builders Association (HBA) of Wake County has joined up with the HBA Durham,Orange,Chatham Green  Building Council for a joint tour of Green Homes this May 3rd and 4th.

The press conference on Monday this week got some coverage on NBC 17 news. It's a shame they didn't get any of the great speeches by Nick Tennyson and Tim Minton, or Bill Beasley's wisdom. Instead they've got home buyers looking at homes, construction work and a pan of the back of the room at the press conference that just happens to land on me for a second.

Climate Change Awareness Day in Chapel Hill

Jan 30th and 31st, Thursday and Friday of this week, are a series of events hosted by UNC in to raise awareness of Climate Change. Following are the events they are hosting which are open to the public.

January 30, Great Hall of the Student Union
6:00 pm: Environmental Social
Meet local governmental leaders, environmental faculty, and other leaders on and off campus. Beverages and finger food will be served.

7 pm: Governmental Panel
Hear local and state government leaders discuss solutions to climate change. Featuring: Robert Cox (Sierra Club President), Eleanor Kinnaird (NC Senate); Pricey Harrison and Ty Harrell (NC House of Representatives); Mark Chilton (Carrboro Mayor)

8 pm: The 2% Solution Webcast
Can we as a nation cut global warming pollution 2% a year for the next decade? If so, what would it take?

January 31
10 am, Cogeneration Tour
Meet at the front door of the Cogen building,

575 W. Cameron Avenue

to get an exclusive tour of our university's cogeneration plant, where UNC gets its power and one of the most efficient coal powered plants in the country!

11:00 - 5:00 pm, Focus the National Carnival
Student music and dance performances, faculty discussion panel, and various other environmental speakers, and educational displays.

4 pm, Fedex Global Education Center building tour
Get a behind-the-scenes look at the newest green building on campus. Meet in the front lobby , 301 Pittsboro Street

 10 pm, Save the Ales
Come by W.B. Yeats to celebrate our cause and learn how climate change will affect our brews while grooving to live music. (Sponsored by Epsilon Eta)

Water Saving Strategies for Builders

Wednesday, February 6 from 9 am to 10:30 am is a chance to learn all about rainwater harvesting systems, rain gardens and water conservation.

The event is aimed at Triangle area builders and is being presented by the Green Home Builders of the Triangle, a Home Builders Association program.

The event is being held at the offices of Rain Water Solutions, 2315 Atlantic Avenue, Raleigh, NC 27604

You'll learn:

• What are rainwater harvesting systems and their components (see them up close!)
• How can a rainwater harvesting system be incorporated into residential design
• How can harvested rainwater be used, and how should it be treated or disinfected
• How much rainwater can be collected from a home's roof in NC
• What are some innovative ways that builders can use to conserve water in new homes
• How can builders achieve water conservation goals in green building certification programs
• What are rain gardens, and how can they be used to handle stormwater runoff
• How does unchecked stormwater runoff affect areas downstream
• And more!

Presented by The Green Home Builders of the Triangle (a joint program of the HBA of Durham, Orange and Chatham Counties and the HBA of Raleigh/Wake County)
$20 for members of the Green Home Builders of the Triangle
$25 for nonmembers

Speakers: Michael Chandler, Chandler Design Build. Michael has been building solar and green homes for over 30 years. He is a General Contractor, licensed Master Plumber and also master tile setter and cabinetmaker. Michael also writes for Fine Homebuilding Magazine on structural, plumbing, and aging-in- place design topics.

Mike Ruck, Rain Water Solutions. As co-founders of Rain Water Solutions, Mike and his wife, Lynn, manufacture their own rain barrels from 100% recycled content. They also design and install complete rain water harvesting systems for residential and commercial clients.

Contact Leigh Scott at 919-493-8899 to register or click here for the flyer.

Blueprint for Greening Affordable Housing

Global Green USA has put out a new book titled, Blueprint for Greening Affordable Housing. It's aimed at affordable housing managers, developers, architects and builders.  And it seeks to help them build affordable homes or modify existing ones for lower energy costs and healthier living. 

The book gives a wide variety of tips and best practices for green building on a small budget.

Tips from Blueprint for Greening Affordable Housing include:

1. Install ENERGY STAR or pin-type fluorescent lighting and ENERGY STAR appliances
2. Design for natural ventilation and passive heating and cooling
3. Design for natural daylight
4. Use trees to shade elevations facing the east or west
5. Install light-colored or green roofs
6. Seal all plumbing and electrical penetrations
7. Install a timer delay or humidistat on the bathroom fan
8. Use low-water plumbing fixtures
9. Use recycled-content insulation, carpet, and drywall
10. Install a carbon monoxide detector

Find the book now on my AStore

ROI Tables for Green Tuneups and Remodelling

I've just discovered GreenAndSave.com which offers ROI tables for various improvements you can make to your home. These show the expected costs versus savings and return on investment (ROI) you might expect from making such modifications.  This is a great resource for comparing the value of improvements.

There are a few points on which I might differ such as windows and skylights. Windows show a payback of 2.3 years which seems very short to me. When I've looked at changing windows I've worked out payback at nearer 10 years. Skylights are another point. In the South they're more likely to cost you money for extra cooling. Skylights a great at adding heat in Summer because they're oriented horizontally for peak Summer sun; and loosing it in Winter because heat rises. Another issue is insulating walls. The cost of tearing out sheet rock in older homes is much higher than the tables indicate. It looks to me as if the cost shown is only the insulation itself not the associated cost of remodeling. But hey, if you're ripping out the sheet rock anyway it has to be done. 

My final gripe is solar attic fans, which do nothing to reduce the cooling demand. 95% of the heat that enters the attic comes through radiation. Increased ventilation does very little to change that. See my Vented Attics post.

Apart from those few issues the resource at  GreenAndSave.com is fantastic. Quite probably much of our differences come from the fact that I'm concerned only with the mixed humid climate of the Southeast which has its own unique challenges.

For the complete ROI tables and topic page with details on over 50 ways to SAVE Money and the Environment visit: Home Remodeling ROI.

My Leaky Ducts Suck

We had been experiencing very dry air at home.  To the extent that we'd wake up with very dry noses and feel uncomfortable.  I should have done this a long time ago, since I know the issue and how to deal with it. But life can derail my best intentions. I finally got down into the crawlspace last week with a bucket of mastic and a can of great stuff. What a great way to spend an afternoon! I got back into the lowest craggiest parts of the crawlspace where I'd never yet gone, and I'm sure I'll never forget.

Basically, I applied mastic to every seam in the air handler and plenum, and I applied it to every part of the duct system that had anything that looked like a seam, right up to the boots. The boot is the part where the duct meets the vents above. The application is not exactly pretty (see photo of my air handler), but who's looking at it? The whole job took me about three hours. Be sure to wear knee pads, a mask and coveralls or very old clothes. One of the initial challenges that slowed me down was simply finding mastic. The big stores around here don't seem to carry it in stock. I eventually asked an HVAC guy where my nearest supply store is and got it sorted out.

While I was down in the crawlspace I found some nice big holes where pipes of one sort or another go up into the house. These were all plugged up nicely with great stuff insulating spray foam.  This will help reduce air leakage some more and keep pests out of the wall cavities.

The most easily accessible part of the floor area is insulated with fiberglass batt. I can only guess it was too much trouble for someone to bother with the rest of the area. Where the fiberglass came up against the duct boots it was badly darkened. This indicates that air was being sucked in and "filtered" by the fiberglass. And that just proves there were leaks where the ducts meet the boots.

The end result is, with a week of cold days to test the changes, we're experiencing much more comfortable air. And we're not waking up every morning with dry chapped noses.  There's a great description of this very same situation by Arnie Katz at Advanced Energy, here.

NC State now has the State's largest PV array

A new 75.6 kW system is now live at NC State University near the RBC Center, as was unveiled Tuesday at a ribbon cutting event. This makes it the largest privately financed array in the State - for now.

Richard Harkrader, this month's green hero and owner of Carolina Solar Energy, started the project back in 2004. His company now plans to build a series of further projects across the State. Plans include systems hosted by businesses, schools, shopping centers and government facilities, all at around 100 kW.

Speaking at the ribbon-cutting event, Harkrader said, “One of our goals with this project and our other solar projects across the state, is to show that solar power isn’t just for people in California and Nevada – it is feasible on a large scale right now, right here in North Carolina.”

He also said, “Photovoltaic solar technology has come a long way. There's no doubt solar power is becoming a viable investment in North Carolina, and will improve the larger projects we build.”

For the full press release click here.

How long will it take for your house to complete fall to ruin?

I thought this article on How Stuff Works, was worth highlighting. It's basically an object lesson in the importance of home maintenance. The article explores the forces at work in a house's decline into ruin if left completely unattended.

So what happens if you simply stop doing the dull household maintenance things like fixing that roof, clearing the gutters, painting etc.? It's no surprise, I'm sure, to readers here that the major agent of destruction is water.  But read the article here for a great exploration of the demise of a structure.

Commercialising utility scale solar power with salt

A new venture called SolarReserve aims to provide reliable, predictable solar generation even at night by using salt.

Their program would save and store captured solar energy in molten salt.  The new solar plant will produce up to 500 megawatts of peak power
.
Read full story on Inhabitat.

Achieving the 7.5 CFM per occupant venting standard

Chandler Design Build use timer delays on bathroom fans along with a few other clever tricks to achieve the balanced standard of 7.5 Cubic Feet per Minute (CFM) of air exchange in their homes. The goal is to provide balanced and filtered make-up air, with a designed exhaust and a balancing intake.

Another of their tricks I like is placing the intake vents in the laundry room since dryers draw out an average of 300 CFM and a nearby intake vent means the dryer won't consume much conditioned air. 

Read the full methodology and tips here.

New Report on Government Incentives for Green Building

Yudelson Associates, a green building consulting firm, has released a new study titled, "Green Building Incentives That Work: A Look at How Local Governments Are Incentivizing Green Development."

There are hundreds of different incentive programs across the country.  Developers need to research what each local jurisdiction offers and need to become involved where incentives are being discussed and adopted. This new survey shows that while developers may be aware of incentives, they often don’t take advantage of the.  That may often be that they need to make quick decisions while governments move too
slowly to enable them. 

This report may, among other things, help local developers lobby proactively by pointing to the sorts of incentives that are working in other areas.

The study is available by free download from the National Association of Industrial and Office Properties web site, downloadable here.

Eco Friendly mobile homes

In another lift from Roland Piquepaille's Technology Trends, I've found a story about an initiative to develop eco-friendly mobile homes. This idea is being driven by a professor of architecture at Mississippi State University (MSU).  His idea of a GreenMobile home is an ultra-affordable and ecological-minded, factory-built housing unit. The first prototypes are expected to be build this March and should sell at about $50,000. They could be used either as regular homes or disaster relief housing.

This story struck me as interesting particularly because I just drove down to the coast and back yesterday and it really is amazing how many mobile home and modular home sales companies there are lining the highways. I'm sure there were at least 10 on my drive, which just underlined for me how popular manufactured homes are.  That would suggest this idea has some real merit.

Largest Corporate Solar in NC now on in RTP

Delta Products has just recently connected a 30 KW solar PV array made up of 160 panels mounted on the roof of their corporate office in Research Triangle Park. It is presently the largest corporate-owned PV system in the state.

It is expected to generate 36 Megawatt hours of power, offsetting 37 tons of CO2 annually.

See the press release here.

The itsy bitsy green kit-home

Anyone not yet ready to build a green home of their own can now buy a miniature house with working solar panels, wind mill, green house and desalination system.  The Power House is available for $149.95 from science-kit distributor Thames & Kosmos. The kit aims to teach children what it’s like to live off the grid.

Power House includes a 96-page full color manual with 70 experiments and 20 building projects. The manual is not just a set of instructions. It is based on a story of a group of high-tech pioneers on an island who must live sustainably with only the resources available to them. As you read their journal entries and learn of their projects and experiments, you build models of the same projects and conduct the same experiments alongside them.  The experiments and projects mimic the tasks the kit’s fictional pioneers must perform.

Top Ten Eco Business Ideas of 2007

I quite like to read Springwise, a newsletter and website that explores new business ideas sprouting around the world. I particularly enjoy their Eco category and the inspiration that comes with knowing about the many clever things that people come up with.

They've done a round up of their top ten ideas from 2007 which is a great read. I recommend it to one and all. My favorite is Eco Assessments for Homes and Businesses. Back in the UK, a few years ago I met with the team behind Encraft which was doing a similar thing but focused on renewable energy. They seem to be doing well, and I think their narrower focus may make for a better business.

And for anyone local that wants to try their hand at one of these, or another eco idea, get in touch. I'm always interested in chatting with entrepreneurs and love exploring new possibilities.

Solar HVAC

Solar air-conditioning units can leverage the sun’s heat to drive either thermal absorption cycles or desiccant cooling.

The unit I'm now supplying in NC is a combination of two well established technologies - solar thermal collectors and absorption chillers.

Absorption chiller air conditioners are already a very widely deployed technology, very popular for large commercial installations in Asia and the US. They are simple, dependable and use no Chlorofluorocarbons (CFCs).   Most, however, are using heat sources other than solar. In part, that's because they require high heat - higher than flat panel collectors can produce.

What has now made solar AC possible for a residential or small commercial application is the emergence of evacuated tube collectors and the availability of smaller scale absorption chillers and smaller cooling towers.

When engineered to run on solar energy the absorption chiller AC units provide the lowest cost to operate and the best return on investment of any air conditioning system in the world. In North Carolina with our excellent 35% State tax incentive the payback can be as short as 2 years. And they can be configured to supply heat in Winter as well.

Our solar heating and air conditioning units can be used anywhere that the sun shines. They are low in operating and maintenance costs and consume very little electricity - which can be supplied by solar PV panels.

[addendum 1/15/08] - These units are currently available only in 10, 20 and 30 ton sizes. A 5 ton unit may become available next year. So they're most applicable to commercial installations.

Contact me for more information and to discuss the applicability of this system for your project. Or read more technical information here.

For a source of more general technical information see this article in Renewable Energy World.

Free online Green Building Course

The National Association of Certified Home Inspectors (NACHI) has provided a free online course on green building aimed at its members, home inspectors.   The course is available and accessible to all, so for anyone who wants a high-level primer or broad introduction, this is a great resource to start out with. It's an excellent overview of materials and practices.

Green house for rent near Saxapahaw

This 1500 square foot custom-designed passive solar home is located approximately 10 miles west of Carrboro near Cane Creek Reservoir, just south of 54.  It was build by Michael Chandler, who I've written about in the "green heroes" category.

The house is surrounded by an intensively gardened outdoor living space with a great playhouse for kids. It has three bedrooms and two baths and has radiant heated floors and an innovative cooling system that circulates well water through the floors and then distributes it into the garden’s drip irrigation system. The house sits on approximately 2 ½ acres of wooded land. The rent is $950/month utilities run about $160. Available now. 

For more details click here.   

Brick making emmits as much CO2 as the Airline industry

Apparently the world's brick making industry accounts for about 2% of global CO2 emissions, about the same as the airline industry. This is according to a story in The Daily Green, which takes its news from Deutsche Presse-Agentur and in turn an article in Wellington's Dominion Post.

I find this a bit startling but not altogether unbelievable. The article refers mainly to handmade bricks out of India and China which are coal fired.  So, I have to wonder where US brick manufacturers stand environmentally speaking.

According to the Brick Industry Association, "The actual embodied energy of brick (the energy required to mine, manufacture and transport it), is approximately 4000 BTU’s per pound or 14000 BTU’s per standard brick. According to the AIA Environmental Resource Guide, that’s less than concrete, glass, steel, or aluminum! And it’s far below the embodied energy of EIFS and fibercement products."

That's interesting but doesn't tell me the CO2 emissions related to US brick manufacture compared to Indian hand made bricks. I'm going to postulate, go ahead and correct me anyone, that Indian and Chinese handmade brick making is far less energy efficient. If that's true then there's a meaningful project for someone to come up with more efficient firing techniques or machinery. Or to come up with some viable alternatives to brick in developing countries, and I'm sure there are many.

Enviro Board - sustainable panel made from straw

Thanks to Jetson Green for bringing this very interesting product to my attention. Enviro Board is an easy to handle and easy to assemble panel product.  The panels are solid (the company uses the term "concrete like") and can be used for either interior or exterior walls, roofs, sub flooring, sound walls and much more. They are fire rated for 1 1/2 hours at a two panel thickness and each panel weighs about 75 lb.. The panels come 8' long by 32" wide and 2 1/4" thick.

The manufacture is basically done by compressing heated straw fibers so that the natural lignins are released to bond the board together. They are extruded through a mill in a continuous process and covered with a durable waterproof paper membrane.

Enviro Board panels offer many benefits such as:

• Energy efficient buildings
• Zero toxicity
• Resistant to fire, termites, mold and mildew
• Earthquake and hurricane stable
• Quickly and easily erected by unskilled labor
• Architecturally versatile
• Ability to mass-produce panels and structures

Because they are made from renewable agricultural waste without the use of toxic glues, the panels can help buildings achieve higher LEED scores.

Homeowners investing in green features

So apparently the weak housing market is turning out to be a good thing for green products and interior designers. With the weaker market, homeowners are staying put and renovating instead of moving. And with the widespread growth in green products this sector is really benefiting.

The Daily Green reports on an article from the San Francisco Chronicle - read the full story here.