Energy Efficient Homes
Electricity produced from the sun is a key component of our program to build healthy energy efficient and zero energy homes. The cost of solar electricity has dropped to a point that it is affordable and if combined with high tech energy efficient building practices can create energy independence for the home owner.
From what I am reading these days the cost of solar electricity will continue to drop in the next few years to a point where it will be no more expensive than electricity produced from dirty sources such as natural gas and and coal.
The all electric home is the future of home building. Imagine having no utility bills, no heating or cooling bills, and being able to plug an electric car into the home’s electric system. All of this is possible today and will save the home owner tens of thousands of dollars over the life time of the house.
Another, and the most important, reason to build an energy efficient home is the environment. A super insulated, air sealed home, sited to the south for passive solar heating and lighting uses much less energy than a conventional home. The addition of solar electricity and solar hot water can create total energy independence for the home owner and reduce heat trapping carbon emissions to zero.
What could be better? A home that is energy independent does not contribute to global warming, and saves the owner tens of thousand of energy dollars over time. Yes that is why we design and build green energy efficient homes.
In future posts I’ll link to web sites that report on the advancements in building and renewable energy technology. While we in the USA are behind in the take up of efficiency and clean energy there are a dedicated core of forward thinking environmentalists, builders, and renewable energy people who are working for change. Energy efficient homes and renewable electricity will contribute to the shift that is underway to a world powered by renewable energy.
Zero Energy Home Project
This is an Energy Independent Cape that we built at the Kelsey Brook subdivision in Freeport, ME. It is a zero energy home entirely producing its own electricity via solar panels on the roof. OUR UNIQUE WALL FRAMING SYSTEM We designed the framing system you can see revealed in this first floor bedroom wall. Our goal is to maximize the R-factor, a measure of a building’s resistance to heat loss. The higher the R-factor,the more efficient the home will be to heat and cool. With this in mind, we frame walls with 2 x 8 studs, as opposed to traditional 2 x 6 construction. Next, we sheath the exterior with 2″ foam board attached to plywood. Finally, we apply 2″ x 3″ horizontal strapping to the inside of this wall. When the wall cavity is filled with dense packed cellulose insulation, our walls achieve an R-factor of 45, Compare this with the R-22 of traditional 2 x 6 frame with fiberglass insulation. At this stage of construction, this new home is well on its way to becoming energy independent.
This exterior wall reveals our unique framing system
Outside view of second floor wall
SUPER INSULATED ROOF FRAMING SYSTEM Once the second floor deck is built, and the walls are framed we are ready to start framing the roof. We use 2 x 12 rafters which, along with 2 x 3 strapping on the slopes, provide the depth needed to insulate the exposed roof ceiling to R-58. The strapping acts as a thermal break. It prevents the framing timbers from being in contact with outside cold and inside warmth.
The start of 2 x 12 roof framing at the gable end
The R-58 in the sloped ceiling is achieved by using 3″ of spray foam along with 10″ of densely packed cellulose. Spray foam has the highest insulating value of any insulation. It is also the most expensive, yet is necessary achieve near R-60
3″ spray foam between roof rafters
After 3″ of foam is sprayed between the rafters, 9″ of cellulose is blown into these cavities. The cellulose is held in place by Insulweb, a permeable fabric that allows moisture from condensation off the roof frame to dry toward the inside of the house. It is vital to the health of the house that this condensation be provided with a way to dry out.
9″ Cellulose secured by Insulweb
BEHIND THE WALLS The framed interior is the skeleton of the house. Studs outline rooms ready for the vital elements that, though hidden, will integrate to make this a comfortable home. At this stage of construction, the electrician and plumber work side by side. Wires thread through walls to outlets. Water lines position for sinks, toilets and showers. At the same time, a sprinkler system is installed, as required by Freeport building code. The Heat Recovery Ventilation System (HRV), essentiol to a super-insulated air sealed house, now appears. Ducts remove stale air from the kitchen and bathroom areas, and provide fresh air to the bedrooms and common areas. The HRV is a critical element in building this zero energy home, providing a safe, healthy living environment.
Interior framing of the kitchen
South side of enclosed house
PULLING HEAT OUT OF THIN AIR This house will be heated by ductless mini-split heat pumps. Unlike traditional combustion heating systems, the heat pump does not burn fuel. Rather, it moves heat from one place to another. The system consists of one to one indoor and outdoor units. The indoor unit acts as the condenser in the refrigeration cycle where heat extracted from the outdoors is brought inside the house through an ultra efficient and nearly silent fan which circulates air through the unit. The outdoor unit acts as the evaporator and gathers heat from the surrounding environment to vaporize the refrigerant. In summer, the heat pump can reverse the process by circulating cool air extracted from the sweltering outdoors. Quieter than a refrigerator and economical to operate, the heat pump can cut the home owner’s heat bill in half. On average, for every unit of electricity used to operate, 3 units of heat are moved. This translates to a comparable $1.50/gallon for oil. The heat pump will pay for itself in 5 years with an expected life of 15-20 years. For information on Rebates and Tax Credits, see Efficiency Maine.
Our solar electric system harvests free clean renewable energy from the sun. The system is ‘grid tied’, meaning that it works without the use of batteries. Rather, it interacts directly with the electric grid, allowing one to either use solar power in real time or bank electricity as credits for use at night or during rainy days.
Anticipation of Solar dictated the siting of the house: First, the roof must face south, and second, the south facing roof space should be located in a shade free area. Ideally, there will be a clear solar window from 9a.m. to 3p.m.
This house features a 5.355 kw array of Canadian solar modules installed on the south facing garage roof. The panels attach easily to standing seams of the metal roof. This system will produce roughly 7.138kWhrs of clean electricity annually, more than enough to satisfy the energy needs of this household. In addition, this system will offset roughly 8500 lbs of CO2 emissions annually. Tapping solar power saves money while protecting the environment.
View of south facing solar panel installation
ENJOY THE VIEW
Triple glazed windows provide an essential component of the zero energy home. They successfully juggle the factors of heat loss and solar gain, while maintaining visual clarity. A good triple glazed casement window provides high levels of insulation and air tightness.
Zero Energy Home Newcastle, Maine
Our latest zero energy home project is underway in Newcastle. The home is being built for Nick and Sandra Barth. It is a 1900 square foot single story home with an attached two car garage.
What separates this homes from others in the neighborhood is that the Barth’s will never have energy bills. The house will be super insulated and air sealed. The Intus windows, made in Europe, are very efficient, With most of the windows on the south side much of the heating will be passive free heat provided by the sun. A solar electric array will provide all the energy needed to power the home.
High performance green homes are beginning to catch on. More people are expressing interest in energy efficiency and solar electricity. When I began to research what it takes to build these high performance homes most people had no idea that a home could be built that would produce all the energy it needed with a roof mounted solar array. Of course back then most people could not afford solar. Today solar electricity has dropped in price to the point where it actually makes sense to install, making Zero Energy Homes affordable.
Our energy efficient green homes cost a bit more to build. The extra costs to super insulate, use better windows and doors, and install a solar electric array are soon recaptured with the elimination of energy bills. The pay back on the extra costs is somewhere between 5 and 7 years. The return on investment begins in the 1st month of occupancy.From an economic view I would say anyone not building a high tech energy efficient home is throwing away a lot money.
The Barth home will be built to the Department Of Energy Zero Energy Ready Home standard and then we will take it all the way to a zero energy home by installing a solar array sized to power the home. To qualify for the DOE rating the home needs to pass testing for air tightness and the levels of insulation need to be verified. The testing will be done by Wes Riley who is a certified HERS professional.
Building a high performance home requires paying attention to air sealing the structure. Air sealing begins at the framing stage of the project. We are using ZIP sheathing which is taped at all the seams. All penetrations from the basement up through walls to the roof need to be sealed with spray foam. Windows and exterior doors all need to be carefully sealed. This is done by using tape to seal on the outside and spray foam applied around the window and door frames.
The moment of truth comes when the home is finished and ready for testing. The process begins with a blower door test. The blower, which is connected to a computer, is placed in an exterior door. The fan will blow air out of the house creating a negative pressure. The computer will measure air flow and will determine air leakage. Fore the home to qualify for the Zero Energy Ready Home designation the leakage needs to be very low.
A bit more to building a Zero Energy Home but well worth the extra effort.
For information regarding the DOE’s Zero Energy Home program :
HERS Rating Freeport Project
Attached please find the Final HERS Report for the Humphrey Residence in Freeport.
Of the 1,000 plus new HERS Rated homes I have evaluated over the years, this home is clearly in the very small group of truly high performance homes.
As we discussed, even though this home did not qualify for the Energy Star Home label due to the kitchen range hood using a charcoal filtering system rather than being vented to the outside, this home is still built considerably better than the minimum energy performance features required by Energy Star.
- This home scored a HERS Index of 20, which is 80% better than the baseline HERS Index of 100.
- This home is very close to being a Net Zero Energy Home ( HERS Index of 0 or lower )
- This home would need to score a maximum HERS Index of 67 to qualify for ESTAR, so it is actually 47% Better than some ESTAR homes.
- This home exceeds IECC 2012 requirements when both Maine Code and ESTAR only require IECC 2009.
Mike – I enjoyed working with you on this project.
Please let me know if you have any questions.
Freelance Home Energy Performance Consultant
Rise and Shine, Maine: It’s Time to Solarize
Welcome to the age of renewable energy and collaboration.
Six years ago in 2009, a group of citizens in Portland, Oregon began a community collaborative program that brings homeowners and businesses together to purchase solar energy installations for buildings in bulk deals that lowers the price per household or business. They called their program Solarize.
“The Solarize approach allows groups of homeowners or businesses to work together to collectively negotiate rates, competitively select an installer, and increase demand through a creative limited-time offer to join the campaign. Ultimately, as the number of residents who participate in the program increase, the cost of the installations will decrease.”
Since its kick off in 2009, Solarize has spread across the country to dozens of communities and several states. Earlier this year, Solarize arrived in Maine through the efforts of a group in Freeport, and now there is also an initiative growing in Sacopee Valley.
As reported by Tux Turkel in the Portland Press Herald, the folks of Solarize Freeport are interested in taking advantage of a 30% federal tax credit for solar installations that drops to 10% at the end of 2016. On top of the tax credit, Solarize Freeporters would see a 10% discount from their bulk purchasing, saving on average $1,500 per building.
So far Solarize Freeport has 39 systems involved, and they are raising more support as a September 30th deadline looms for the next batch of purchasing.
In the absence of, erhm, a more “supportive” political climate, it is encouraging to see Mainers taking matters into their own hands. More and more we are seeing this kind of self-reliance replacing the old dependency models on big fossil fuel industries.
With fossil fuel energies becoming more expensive and scarce, alternatives like solar power will soon be the norm. It’s been Island Carpentry’s plan to be ahead of the curve on green building. Why wait? Now is the time to join the solar revolution!