Tulus Simatupang of British Columbia, Canada won the Grand Prize for the 2013 Digital Photo Contest sponsored by The Nature Conservancy. The photo that won is of a heron in flight with a red-winged blackbird. It was a top choice by judges and also received the most 1st place votes from supporters. Visit The Nature Conservancy here to see all of the results for the contest.
What green building techniques and design options make sense? Which ones save you, the homeowner, a few greenbacks in the long-term? Here I’ll share my experience with energy efficiency choices while building a two-story, 40 ft. by 20 ft. home addition. But before I jump into the details, I’d like to tell you I opted to be the “Homeowner General Contractor” (Homeowner GC) for our addition project. Let me explain.
I have more than a few years of project management experience as well as an extensive environmental consulting background. I’m a registered professional geologist, entrepreneur, and the former publisher/editor for environmental magazines. For the record, I know a little bit more than your average homeowner about the environment and what “green” really means. So what do you do when it comes time to consider green building techniques and make purchasing decisions for a construction project?
For starters, I did my homework and extensively researched building methods and the science behind numerous green-building recommendations. Once I understood how certain things worked (or didn’t work), it was a lot easier to evaluate not only the building design choices but also the sub-contractors bidding on the tasks at hand. One more thing, before making the final decisions I loaded up the spreadsheet and ran the numbers. I wanted to know the potential return for the green investment (ROI). After all, green is the color of money as well.
Below I’ll explain a few green building techniques I went with for our addition project based on my findings. And in addition to that, why the investment was made to upgrade beyond local building code requirements, in certain cases.
Structural Insulated Panels (SIPs) – Walls only (not the floors or the roof): Structural Insulated Panels (SIPs) were chosen for the walls. I went with 6 1/2 inch SIP walls with an R-Value of 24. In our area (Central Virginia), this exceeds code requirements. One important thing to note: SIPS “perform” at a much higher R-Value than a stick-built wall. For example, a 4 1/2 inch stick-built wall with R-13 insulation likely only gets you around R-9 performance. SIPS perform a lot better. You can either spend a little more for a SIP wall upfront (with respect to material costs) or pay more in energy bills month after month, after month… Several builders and General Contractors I interviewed told me SIPS cost too much compared to stick-built walls; they really don’t when all aspects of the project are considered. Below are a few reasons why.
Significantly less labor is required to put up a SIP wall compared to a stick-built wall. The SIP walls were installed in three days. A comparable stick-build 6 1/2 inch wall finished with insulation and electrical chases cut in would have taken about three weeks; according to the local builders/General Contractors that I interviewed for the job. With SIPS you generate less waste at the construction site which means less labor moving trash around and less waste disposal fees. You also save on labor when it comes time to run the electrical wires; chases are cut into the SIPS at the factory and it takes less time to rough-in the electrical. Another benefit is the fact that you need one less sub-contractor involved in the project given you don’t need to wait for the walls to be insulated once they are put up (they come insulated). I could go on but I won’t. Once you truly understand all of the construction costs involved with the walls, the numbers tell the story. SIPS are worth the investment and the ROI is hands-down better than a stick-built wall based on the true cost of construction. I have more information about SIPs here for those interested.
Conditioned Crawl Space
For our addition, I basically had to have a crawl space – the existing home my wife and I were adding on to has a crawl space. We wanted level floors going into the addition. Therefore, a conditioned crawl space under the addition was added to the project cost. If you “must” have a crawl space, condition the space. For me it was a no-brainer; less moisture under the floors, less air infiltration, fewer rodents/insects, and a conditioned crawl space allowed me to run the HVAC ducts under the floors in “conditioned space.” I’m convinced it saves energy and maintenance costs associated with the HVAC system. For the crawl space wall insulation, I went with 2″ Thermax on the exterior walls and a 10 mil liner. I considered a 20 mil liner but the 10 mil liner was sufficient given I don’t plan to store anything in the crawl space or frequent it often; the 10 mil liner seems plenty thick to me.
When designing the roof trusses, I increased the “heal height” (where the roof meets the top wall plate) by a foot. Why? The extra foot of space on top of the wall plate (basically, in the attic) allows more attic insulation where you need it; at the pinch point where the roof meets the walls. According to several energy efficiency studies I came across while researching, homes lose a lot of energy where the insulation basically goes to zero thickness where the roof line meets the walls. This made sense to me so I had the truss engineers add the extra heal height. It didn’t add much to the costs of the roof trusses.
Rainscreen – Underneath the Siding
To lower the risk of wall rot, it makes sense to provide a ventilated air gap between your siding and your sheathing. I went with an advanced building technique for the siding known as a rainscreen. SIP manufacturers, as well as many experienced siding professionals, recommend “rainscreens” for the exterior walls under the siding. Rainscreens using furring stripes are also recommended if you are using spray-foam insulation on your walls. It is smart building science and I believe it might be code a decade from now – already is in some jurisdictions. Basically, a rainscreen allows the wall to dry out much more efficiently. Even with Tyvek house wrap (which we also used), the walls under your siding will get wet and you want them to dry. Rainscreens allow that to happen.
Rainscreens do add additional costs to the siding budget; both in material and labor. In our case, I removed the old pine-board siding from our existing home since we wanted consistent siding for the entire home. We ripped the 3/4 inch pine-board siding and used it for furring strips for the rainscreen. This reduced our material cost of construction but added more labor costs. On the other hand, the rainscreen lowers your long-term maintenance costs (less frequent painting, siding replacement, etc.) and extends the life of your walls.
Our rainscreen includes Cor-A-Vents to enhance performance. Cor-A-Vents allows the gap between the siding and the sheathing/Tyvek house wrap to vent and stops insects from getting behind the siding. The Cor-A-Vent added to the overall project cost as well. For more information pertaining to rain screens, read All About Rainscreens on the Green Building Advisor website.
Energy Efficient Water Heater
I purchased and installed a GeoSpring Hybrid Electric Water Heater (GE GeoSpring 50-Gallon Hybrid-Electric Heat Pump Water Heater – ENERGY STAR) to lower our energy costs. This water heater is a significant upgrade from your standard water heater. Although it costs more than the typical water heaters, it pays you back year after year. It is one of the most efficient 50-gallon water heaters, using 62% less energy and saving $365 a year on utility bills (SOURCE: GE GeoSpring). What makes this water heater so energy-efficient are the compressor and evaporator that are incorporated into the unit to draw in ambient heat from surrounding air, using two variable-speed fans. When in heat-pump or hybrid mode (warmer months), the unit exhausts cool, dry air; it lowers humidity and cools the room while heating the water. Basically, the water heater is an air conditioner too.
For more information on energy efficient water heaters, read Choosing the Best Energy Efficient Water Heater.
Upgraded HVAC System – Conditioned Space
I replaced our existing HVAC system which was 13-years old while building our addition. We needed a HVAC system for the addition and we needed a replacement for the old unit serving the rest of the house. During the design phase, I decided based on extensive research that the best thing to do was install the new HVAC system inside the building envelop. Therefore, we built a utility room, conditioned the room (it is heated & cooled), and subsequently located the new HVAC unit inside instead of in an unconditioned attic. Also, the majority of the ducts are now within conditioned space. Locating your HVAC system and ducts within conditioned space reduces your energy use, lowers maintenance costs, and extends the life of your HVAC system. It is a good investment if you think about it during the design phase of the construction project. It really doesn’t cost much more to do when it is considered early in the design process.
I found several articles that discussed the energy loss associated with second floor joists and the rim board that holds the joists. When joists are set on the wall plate the joists/rim extends to the outside of the wall. Insulating a rim is difficult to get right and it is a common area for energy loss according to energy audit results. A better way to build includes hanging the second floor joists “inside the building envelop” (joists don’t contact the outside at all – no need to try and fill every void at the end of the joists at the rim board). Hanging the joists inside is more energy efficient and results in a stronger building according to engineering data (search online, numerous articles support this conclusion). The figure to the right shows how we constructed our addition with hanging floor joists.
Energy-Efficient Dryer Vent
One of the easiest things I did to further reduce air infiltration and save energy was replace the old dryer vent exhaust seal (Energy-Efficient Dryer Vent Seals – HEARTLAND Dryer Vent Closure). I replaced the “builder grade” exterior dryer exhaust vent with one designed for energy efficiency; it seals when not in use. The old vent was basically a hole in the wall and the washer/dryer area in our laundry room was freezing cold during the winter. The new vent was inexpensive and easy to install. Basically, it lets warm air escape when open and prevents cold air (or hot air in the summer) from entering when closed. The dryer vent seal also prevents insects and rodents from entering your home. Any homeowner with basic DIY skills can install one and start saving money right away. I could not find one at Home Depot or Lowes so I purchased our dryer vent online.
How did we do?
Our electric bill received the other day (January 2014) was LESS than our January 2013 electric bill even after adding about 1,600 sq. ft. of additional space to our home. I was amazed given it was a really cold January this year and we added our energy efficient water heater to the home before January 2013.
Nest, the company that makes what they claim to be the “next generation thermostat” is facing a few challenges. Out-dated HVAC systems, Wifi connectivity, and vocal, unhappy customers during a national cold spell are in the forefront in today’s news. TechCrunch discusses the situation on a recent blog post here. You can learn more about the product and read reviews on Amazon – Nest Thermostat product info and reviews.
I seriously considered purchasing a “smart” Nest thermostat when we built a large addition on our home last year. We upgraded our HVAC system throughout the home. We installed a Carrier Infinity HVAC system and Mitsubishi Mini-splits. The Carrier is a 3-zone system and 3-thermostats; the mini-splits have their own thermostats. In our case, the cost of the Nest for the potential savings appeared questionable when compared to other energy saving investments and the respective ROI (6″ walls, insulation, smart building techniques, etc.). Today’s programmable thermostats are pretty good w/o being “smart” – the stupid things have worked (always) as advertised.
On Nest’s website they claim, “Programming thermostats is complicated and irritating – but an un-programmed thermostat can waste 20% of your heating and cooling bill. So the Nest Thermostat programs itself.”
Programming our standard thermostats wasn’t complicated or irritating – it was simple. One control panel programs all three; it took about 20 minutes. I focused on energy savings when I programmed them; tweaked them during the first few months. I likely have them set for less demand then the Nest would allow based on living habits; I only turn them up/down when I feel uncomfortable in the home. They appear to be saving us money without the need for software upgrades, wifi connectivity, etc.
WRT energy conservation and saving money, the smart thing to do is focus on containing the energy you generate; over insulate the attic, stop air infiltration, etc.
Simple is a solution.
Traveling for the holidays? To improve your gas mileage consider changing your oil and air filter to improve your ride. I’m always amazed at how much better my car runs after changing the oil and air filter. What else can you do to increase your fuel mileage?
Make sure your air pressure in the tires is right or slightly over-filled. Also, change your “cabin air filter” – just changed mine. It was nasty, filled with leaves, dust, etc. The automobile service center that changed my oil wanted $50 for a cabin air filter. That’s just too much to pay for a cabin air filter. I declined and picked one up at Advanced Auto on the way home for $19 and changed it in the parking lot in less than 5-minutes.
Not all cars have a cabin air filter but most newer cars tend to have one. If your car has a strange odor when you turn on the heater or air conditioner, or if it seems like the fan doesn’t work like it once did, it is likely time to change your cabin air filter.
Why change your cabin air filter?
Changing your cabin air filter (you can buy on from Amazon) does several things for you: improves the air quality inside your car, reduces strain on your heating and cooling system (less maintenance and wear), and a new air filter allows you to run the fan at lower speeds which improves gas mileage.
How do you change a cabin air filter?
It is relatively easy. In most cars, the cabin air filter is located behind or just under the glove compartment. I found a great website that includes videos on changing the cabin air filter; they had a video for all of our cars. Check out: Car Care Kiosk. It is an excellent website for automobile maintenance and “how to” automobile maintenance videos.
Can you benefit from a Cool Roof? Or are you better off investing in more insulation? No doubt, a cool roof can help many building owners save money while protecting the environment but not everyone should rush to get one.Your money might be better spent on attic insulation depending on where you live as well as your specific attic situation.
The U.S. Department of Energy has published an excellent guidebook on cool roofs (link below). The guidebook was created to help builders and home owners understand how cool roofs work. Read more
Earlier this year, I wrote a post on the Pros and Cons of Geothermal Heat Pumps (GHP). As it turns out, there is more to the story. I am in the process of evaluating HVAC systems for an existing home that is getting an addition. The addition is almost the size of the existing home; a new HVAC system is required as you can imagine.
After looking into several HVAC options with a focus on GHP, the consensus is to first focus on “tightening” the envelope of the existing home while considering the most effective methods of building an energy efficient addition. And, do this before worrying about your HVAC considerations. For my wife and I, it comes down to “first things first.” And, first on our agenda is “air infiltration” and insulation.
We are currently building an addition to an existing 1930s home. Understanding the energy use in the existing home and the addition we are building (or the home/addition you plan to build) is, IMHO, by far the most important aspect of HVAC considerations that come later. A “tight” home requires less energy to heat and cool, which in turn requires a significantly smaller HVAC system. And, what that means is a much lower overall energy bill.
It is important to note that lower overall energy use “increases” the “pay back time” required to recover the additional capital costs of a geothermal system.
Paying to “save energy” by investing in better windows, doors, and stopping air infiltration (conditioning your attic and crawl-space, for example), gives you the highest ROI (return on your investment). But, investing in “energy efficiency” leaves you with less money in the overall project budget. So, you need to consider this, is it better to invest in a GHP system or first invest in energy efficiency?
Cutting a big energy bill in half saves you a lot more money than cutting a relative small energy bill in half (basic math). For example, a poorly insulated home may have a $400/month energy bill on average, cut that in half and it saves you $200/month ($2,400/year). But, a “tight” home of the same size (sq. ft.) may only have a $150/month energy bill; cutting that in half only saves $75/month ($900/year).
Over the course of 1-year, the difference is $1,500/year and $15,000 over 10-years. My point here is if you have a well insulated home (SIPs, conditioned attic and crawl-space, great windows and doors, etc.), the initial capital cost of geothermal systems (GHP) requires a lot more time to “pay you back” because your overall energy use is low and so is your savings, in the short-run.
Say you have or plan to build a tight, energy efficient home and your monthly utility bill with a traditional HVAC system is projected to be the $150/month example above. Say installing a GHP cuts that in half to $75/month. If the GHP system costs you $15,000 more to install than it takes over 10-years to “break-even” (I’m assuming the $15,000 in the bank would be worth more 10-years from now; maybe $20,000).
What I have concluded after a significant amount of research is this; a home that uses significantly less energy because it was built or remodeled to be very energy efficient may not benefit “financially” all that much from a GHP system due to the initial capital cost involved.
Unless you have a huge McMansion or you are using the GHP to also heat a pool, etc., may I suggest you run the numbers for your project? And, definitely consider the best solution of all, invest in cutting your total energy use by “tightening” up the home and stopping all possible avenues of air infiltration.
In short, first take a hard look at the energy efficiency of your home or project before considering any of the possible HVAC systems. There are several new HVAC technologies (mini-splits, high efficiency heat-pumps using air – traditional type systems) that are making GHP a hard sell for energy efficient homes of say 4,000 t0 5,000 sq. ft. or less.
Remodeling a home is possibly one of the highest levels of “green.” It is one of the best sustainable housing initiatives around. While researching the remodeling industry I came across the website dubbed, Home for Life. The site includes a wealth of resources that explain opportunities to upgrade an existing home’s energy and resource efficiency to reduce environmental impact. The website is a product of Remodeling Magazine, a Hanley Wood publication. Read more
Do attic fans lower the cost of cooling your home?
Are solar attic fans worth installing? Common sense suggests they would be but are powered attic fans really a good idea for energy efficiency based on research and science? I have a master’s of science degree and my initial belief was it made sense. It just seems logical that a cooler attic would lower the cost of cooling the house in summer. While researching radiant barriers for the attic and reflective paint (Kool Seal Premium White) for our metal roof, I came across a few articles strongly suggesting powered attic fans were a dumb, and possibly dangerous, idea based on science. Here’s what I found so far and why I removed my attic fan:
- The Scientific Spin on PAVs (powered attic ventilators – fans): Cooling off hot attics with powered attic ventilators (PAVs) seems like a good idea. After all, doesn’t cooler attic air mean less work for the HVAC system, longer shingle life, and reduced energy costs? Unfortunately that’s more myth than fact.
- Drawbacks Of Powered Attic Ventilators:Powered attic ventilators, already suspected of using more energy than they save, can also create excess moisture, structural problems, discomfort, and combustion safety problems for home occupants, according to a recent study. John Tooley of Natural Florida Retrofit, and Bruce Davis of Alternative Energy Corporation’s Applied Building Science Center in North Carolina, presented “The Unplanned Impacts on Houses by Powered Attic Ventilators” at the 1995 meeting of the Energy Efficient Building Association.The paper describes research conducted on eight homes over a period of three months. As a result of this research, Davis said that he wouldn’t recommend the use of powered attic ventilators. He emphasized, “If someone chooses to use a powered attic ventilation strategy, they need to do additional performance tests and take responsibility to be sure that it won’t cause other problems.” The potential for hazardous conditions is particularly high in homes with combustion gas appliances, because the ventilators can create negative pressures that cause backdrafting.
- Energy Star: Attic Fan Ventilation – Attic fans are intended to cool hot attics by drawing in cooler outside air from attic vents (soffit and gable) and pushing hot air to the outside. However, if your attic has blocked soffit vents and is not well-sealed from the rest of the house, attic fans will suck cool conditioned air up out of the house and into the attic. This will use more energy and make your air conditioner work harder, which will increase your summer utility bill.
- Ask the Builder: Powered Attic Fans – Attic Insulation Facts: “I used to recommend PAVs [powered attic ventilators – fans] for houses, but I don’t anymore.”
- Building Science, Unvented Roof Summary Article
The best solution appears to be making sure your attic is well insulated and well-ventilated using passive vents and natural air flow. Inspect your attic insulation and ventilation, or have a contractor do so for you. Just add more insulation or natural (passive) ventilation, if needed. Both measures will reduce the cost of cooling and heating your home; no electricity required and they are perfectly quiet.
ADDITIONAL ENERGY EFFICIENCY RESOURCES
- Contact the local power company website and local energy associations for more information on constructing an energy efficient home in your area.
- Building Science Corporation, Unvented Roof Summary Article: Excellent resource with in-depth research and hard-core science. Building Science is dedicated to teaching and providing factual information concerning building science and energy efficiency. This resource is used extensively by builders “in the know” when it comes to energy efficiency.
- Building Science Guides and Manuals: Good place to start if you want reference documents for some of the most important building science topics.
- Building Science Information Sheets: Fact sheets and overviews; another great place to start for those relatively new to the field.
- Energy Star : The Energy Star website has extensive information on energy efficiency.
- Geothermal Heat Pump Consortium: Geothermal is the most energy efficient method known today for heating and cooling. However, you will benefit by first making sure your home or building is insulated properly and as air tight as possible (within the limits of the appropriate building codes and safety concerns) before considering an expensive geothermal system.
ENERGY EFFICIENCY PRODUCTS
Whether or not you are using an attic fan and you own a fireplace, a great product to consider is a fireplace plug. Battic Door sells several energy conservation products including a simple fireplace plug; stops drafts and saves energy by sealing the chimney when not in use:
The Fireplace Draft Stopper is an inflatable urethane chimney plug balloon pillow measuring 38″ x 16″. A round Fireplace Plug is also available. It is quickly and easily installed in the fireplace just below the damper level. The Fireplace Plug can be adapted to work in almost all fireplaces. Even if you have an unusual construction, the Fireplace Plug can be successfully installed in less than 2 minutes.
The Fireplace Plug is provided with 5 “slittable” areas that can be cut to provide an opening for a damper handle. As the Draftstopper is inflated it seals around the damper handle sealing the opening (helps reduce energy costs). Easy, quick and clean installation.
My metal roof was red, hot, and desperately needed painting. After spending some time inspecting the roof, I quickly realized how incredibly hot the red paint became even on a modestly hot spring afternoon. Why repaint the roof red since it gets so hot? I thought there must be a better solution so I started investigating roof paints. Fortunately, I wasn’t the only one wondering if a lighter-color roof would reduce heat gain inside the attic and save energy. Also, I quickly learned a lot about “reflective” paints, radiant heat, and the best ways to insulate the attic to reduce cooling and heating costs.
One research article I found informative and one I recommend reading is, Cool Roofs For Hot Climates by Dan Parker, a senior research scientist with the Florida Solar Energy Center (2003). The following is from the article:
Reflective roofs work because they stop the rooftop heat before it ever gets going. The sun’s rays hit the roof at the speed of light, and at the speed of light they bounce back into space. White or light-colored materials work best, but some new dark pigments reflect enough invisible infrared radiation to reject a lot of solar energy. And whether you’re applying tile, metal, membranes, or even asphalt shingles, choosing a more reflective version seldom adds cost.
The figure below graphically depicts the best solution for energy efficiency is a reflective white metal roof:
After reading this article and numerous others, I painted my metal roof with Kool Seal® Premium White Elastomeric Roof Coating which I purchased at the local hardware store (ACE Hardward has it here in Richmond, VA).
Additional Metal Roof Information
Roof Costs and Energy Savings: According to the Metal Roofing Alliance, white-painted metal roofing has the highest solar reflectance value of any roofing product available and can save you up to 40% of your annual energy bills.
According to statistics from McGraw-Hill Construction Research and Analytics®, the number of homes with metal roofs has more than tripled over the past decade, moving metal from 3% of the overall U.S. market to 10%.
Some homeowners’ insurance programs allow discounts for homeowners with specific weather-resistant metal roofing products. Contact your insurance agent to determine if your home qualifies.
Photo taken after the 1991 Oakland, California firestorm. Burning embers destroyed all of the homes in the neighborhood, except the masonry home that was roofed with Stone-Coated Steel Roofing. While all of the neighbors fought (without success) to save their homes by watering down their asphalt roofs, burning embers did not ignite the steel roof. The house with the steel roof survived while all others around it were destroyed. (SOURCE: Metal Roofing Alliance: Lower Your Insurance with Weather-Resistant Metal Roofing)
Kool Seal® Premium White Elastomeric Roof Coating
FEATURES AND BENEFITS
(SOURCE: Provided by the manufacturer, see product description, surface prep, etc. here – PDF)
- Energy saving up to 35%
- Reflects 90%+ of the sun’s rays
- Designed to be durable in any climate
- Higher solids for better coverage
- Forms a thick rubber-like blanket of protection
- Expands and contracts – clings to your roof in all temperatures
- Protects against moisture
- Cured elastomeric film is mildew and algae resistant
- Helps to absorb sound
- Environmentally compliant
- Soap and water cleanup – while wet
Energy Efficient Roofing Video by Tod Miller
Other Useful Articles Pertaining to White Roofs:
- Metal Roof Retrofit on a Hurricane Damaged Home by: Dave Chasar, PE. A before/after energy comparison of shingle roof verses white metal roof replacement; includes monitored data collected at the home over several years.
- Metal Roofing Alliance – www.metalroofing.com
- The Cool Metal Roofing Coalition – www.CoolMetalRoofing.com
- Energy Star – www.EnergyStar.com