In addition to the ever important blower door test, use a fog machine to expose leaks from the outside of your home. Reverse the fan to pressurize the house rather than depressurize which is what a blower-door test does. Place a cheap fog machine in the house, stand outside and watch (hopefully not) the fog seep out of the undiscovered openings. Do this before the drywall is hung.
Saturday, November 17, 2012
Duluth, MN, passive house example
A passive solar home in Duluth, Minnesota
This above link describes a passive solar home constructed in 2009 in Duluth, Minnesota. I like the concepts of the house and their thought process but think that it could have been less expensive to build and slightly more efficient using a few different methods.
Important to note: Duluth, MN, yearly heating degree days are very similar to Fort Kent. Approximately 8,000 for Duluth versus 8,300 for Fort Kent.
This above link describes a passive solar home constructed in 2009 in Duluth, Minnesota. I like the concepts of the house and their thought process but think that it could have been less expensive to build and slightly more efficient using a few different methods.
- Spray EPS foam walls with 4'x8' foam sheets to break the thermal bridge and/or with offset 2x6 wall studs. Less labor intensive too.
- Instead of foam-cut sheets to fit between the floor joists, again use spray foam to offer a better R-value while make for a more airtight section. Again, less labor intensive.
- As they mentioned, at least 10% of the floor space to be high performance windows on the south facing elevation, instead of their claimed 8-9%.
- The article doesn't go into detail about the air sealing around the window frames. Taping in this area is a must.
Important to note: Duluth, MN, yearly heating degree days are very similar to Fort Kent. Approximately 8,000 for Duluth versus 8,300 for Fort Kent.
Solar PV versus solar thermal?
The following is an insightful article comparing solar pv (solar panels) to solar thermal (evacuated tubing) systems to heat your domestic hot water.
This and other information that I have collected is pointing me more in the direction of heating both my home and domestic hot water with solar PV, not solar thermal; its simplicity paired with a super efficient heat-pump water heater or electric-resistance water heater would foreseeably make for a less complicated, more hassle-free, higher efficiency system.
Thursday, November 15, 2012
Passivhaus defined
The Passivhaus movement was developed by Swedish professor Bo Adamson and German professor Wolfgang Feist in 1988. They developed a realistic method of building using super efficient materials and efficient concepts that saves 80-90% of home heating costs as compared to conventional new home construction. The first passive house was built in Germany in 1991, now with about 25,000 houses worldwide. Passivhaus is now the world standard in energy efficient construction regardless of climate and location. For a house to be considered "passive" it must incorporate specific building characteristics including the majority of heating from the sun, a super insulated and airtight shell and mechanical air ventilation to achieve a specific volume/hour of air exchange. To be considered "passivhaus certified" (not to be confused with net-zero homes) the heating load must not exceed 15 kWh/m2 per year. The Passivhaus Institute certifies building products which meet or exceed their efficiency standards. Additionally, they have developed a powerful software called PHPP (passive house planning package), a highly accurate energy modeling tool used to calculate the energy requirements of any structure (accuracy of +/- 0.5 kWh).
Eight Building Principles (all to be explained further in future posts)
1. Super Insulation: significantly reduces heat transfer between the inside and outside of the home. High R-values (conversely, low U-values) resist the flow of heat down the temperature gradient. Not only are walls and ceilings considered, but at the ground level and windows as well.
2. Super Airtight Envelope: very simple-if air is allowed to move back and forth, heat is lost. At least 40% of a home's heat is lost through ventilation (ie. leaks) even in new construction! But doesn't a house need to "breathe"? Sure it does, but I want to know exactly where it is breathing.
3. Thermal Bridging: a thermal break is needing to separate the cold to hot surfaces. The best insulated wall in the world will transfer heat if thermal bridging is not considered.
4. Heat Recovery: 90% of the heat from the air that mechanically moved out of the house is recovered and brought back into the house. The energy transfer is reversed in the summer, keeping the house cool.
5. Mechanical Ventilation: related with #3. Because the house is virtually airtight, it needs to breathe to maintain proper humidity levels. New super high efficient air exchange units (that recover the heat-see above) move the entire home's volume of air in a number of hours, replacing it with fresh outside air and virtually uses no electricity to do so.
6. Highly Insulated Windows: one of the building criteria that people think they are achieving but in fact are not. There are many window companies that provide surprisingly high R-values (upwards of R-12), unfortunately none of which are manufactured here in the United States. Certain Energy Star certified windows insulate well (for a limited lifespan-more on this later) but do not let enough solar heat through the glass to provide the necessary heating from the sun. This is not to mention specific glazing and frame insulation options.
7. Energy Modeling: using the PHPP modeling software, the efficiency of a design can be calculated before it's built with astounding accuracy. Prediction of energy usage is a vital component in the design process.
8. Passive Solar Gains: amazing to me to see new homes facing completely the wrong way or having too many windows on the northern exposure. The home requires many insulated windows on the south facing side and limited windows on the west and north sides. Conversely, avoiding overheating in the summer with planned shading/overhangs.
Solar site planning
For a passive solar home to receive the intended ~40% of a home's heat from the sun, proper positioning is crucial. Solar azimuth angle, solar elevation angle and hour angle based on our latitude and time of year need to be determined for the site of the home.
Below is a map of the path and solar rays for winter solstice, December 21, the day with the least amount of sunlight. If our home can receive the maximum amount of sun on this day, we can assume the remainder of the year will provide more than enough sunlight for effecting solar heating.
Here is another solar diagram which shows the solar elevation angle corresponding to the solar azimuth and hour on that same day.
At noon, when the time of the day when the sun is at its peak (in this case 19.06 degrees), the azimuth angle is 186.6 degrees. This means we need to orient the southern facing elevation perpendicular to this heading to receive the most direct sunlight on the day with the least amount of sun.
Here is another chart that represents the same data in a different way.
Here is an example of the opposite solar calendar; summer solstice on June 21st, the most daylight of the year. Notice the dramatic difference of the angle of elevation and time of day of rise and set as compared to December 21.
The solar azimuth at noon changes to 193.3 degrees. As stated above, our south facing elevation facing 186.6 (based on December 21 solar geometry) will not be directly perpendicular to the house at this time of year which is advantageous on keeping the house cooler.
Aside from eyeballing this data while at the lot, I have not applied these measurements to the site itself. I will be using an inclinometer to determine solar light based on the time of day on December 21 and hopefully get at least 9-3pm sun. Fingers crossed.
Below is a map of the path and solar rays for winter solstice, December 21, the day with the least amount of sunlight. If our home can receive the maximum amount of sun on this day, we can assume the remainder of the year will provide more than enough sunlight for effecting solar heating.
Here is another solar diagram which shows the solar elevation angle corresponding to the solar azimuth and hour on that same day.
At noon, when the time of the day when the sun is at its peak (in this case 19.06 degrees), the azimuth angle is 186.6 degrees. This means we need to orient the southern facing elevation perpendicular to this heading to receive the most direct sunlight on the day with the least amount of sun.
Here is another chart that represents the same data in a different way.
Here is an example of the opposite solar calendar; summer solstice on June 21st, the most daylight of the year. Notice the dramatic difference of the angle of elevation and time of day of rise and set as compared to December 21.
The solar azimuth at noon changes to 193.3 degrees. As stated above, our south facing elevation facing 186.6 (based on December 21 solar geometry) will not be directly perpendicular to the house at this time of year which is advantageous on keeping the house cooler.
Aside from eyeballing this data while at the lot, I have not applied these measurements to the site itself. I will be using an inclinometer to determine solar light based on the time of day on December 21 and hopefully get at least 9-3pm sun. Fingers crossed.
Wednesday, November 14, 2012
Site planning
A lot of thought and consideration has been made regarding where exactly we want our house. Making a decision has been based upon a number of factors including land availability, site access, location from work/school, scenic views, road length, utility installation costs and price. As our our entire design idea is based upon passive solar, geography, placement and sun availability had to be one of the biggest priorities.
As a passive solar house costs ~15-25% more as compared to a traditional build, we needed to take into consideration the extraneous costs associated with the site(s) to stay within our budget. Of the two sites available, one was perfect for a passive solar home, allowing for unobstructed sun from at least 9am-3pm (in the winter) which is necessary to provide sufficient solar heating for a home. It had magnificient views (although our orientation would not be looking at it) but its lack of tree cover from the west and north made it exposed, with the winter wind buffeting and trying to penetrate our building envelop. It turns out that our driveway at this site would have been too costly and time consuming to maintain in the winter. As it was located in a field it would have been ~1,400 feet long with 2 steep sections, clearing drifting snow would have required a large and very costly compact tractor (upwards of ~$40K). It was also about 4 miles away from town on a busy road; not a far commute by any means but a challenge once the kids got older and had the option and independence of biking to town/school and being with friends. Moreover, installation of utility poles would have cost at least $6K (and potentially much more by the time we build as prices will be increasing substantially in the near future as our local utility company adopts Bangor Hydro pricing ). Lastly, ledge would not have allowed for a basement which we wanted for a garage, work shop and storage.
The second site is about 1 mile from the center of town and offers a slightly shorter and more gradual climb from the main road. The road will end up being about 200 feet shorter but most importantly it will be protected from the wind so that snow drifts won't be an issue. It is a heavily wooded lot but will be harvested to allow for the maximum sun exposure. The amount of clearing is still being determined. I'm thinking about harvesting several trees on the lot to make into beams for the great room. They are mostly hardwood, consisting of yellow birch, beech and maple species. We estimate the tree harvesting from the road and the lot will pay for the ground work and road construction. Getting electrical lines will be much less expensive than the first site. Currently, Maine Public Service Company provides the first 300 feet for free and then charges $6.22 per foot. Our house location would be approximately 350-400 feet from the nearest utility pole, making it substantially cheaper than the first site.
Below is the proposed road. Its length is ~1,100 feet with a steep early decent from the main road, leveling off towards a stream and a gradual rise to the home site.
Below is the proposed utility line from my father's existing pole near his garage. Its length is ~370 feet.
One thing that has remained constant throughout our site determination is our home's orientation to take in the most sun possible during the winter months. 190-195 degrees is required for our south facing windows.
More on sun geometry coming up.
As a passive solar house costs ~15-25% more as compared to a traditional build, we needed to take into consideration the extraneous costs associated with the site(s) to stay within our budget. Of the two sites available, one was perfect for a passive solar home, allowing for unobstructed sun from at least 9am-3pm (in the winter) which is necessary to provide sufficient solar heating for a home. It had magnificient views (although our orientation would not be looking at it) but its lack of tree cover from the west and north made it exposed, with the winter wind buffeting and trying to penetrate our building envelop. It turns out that our driveway at this site would have been too costly and time consuming to maintain in the winter. As it was located in a field it would have been ~1,400 feet long with 2 steep sections, clearing drifting snow would have required a large and very costly compact tractor (upwards of ~$40K). It was also about 4 miles away from town on a busy road; not a far commute by any means but a challenge once the kids got older and had the option and independence of biking to town/school and being with friends. Moreover, installation of utility poles would have cost at least $6K (and potentially much more by the time we build as prices will be increasing substantially in the near future as our local utility company adopts Bangor Hydro pricing ). Lastly, ledge would not have allowed for a basement which we wanted for a garage, work shop and storage.
The second site is about 1 mile from the center of town and offers a slightly shorter and more gradual climb from the main road. The road will end up being about 200 feet shorter but most importantly it will be protected from the wind so that snow drifts won't be an issue. It is a heavily wooded lot but will be harvested to allow for the maximum sun exposure. The amount of clearing is still being determined. I'm thinking about harvesting several trees on the lot to make into beams for the great room. They are mostly hardwood, consisting of yellow birch, beech and maple species. We estimate the tree harvesting from the road and the lot will pay for the ground work and road construction. Getting electrical lines will be much less expensive than the first site. Currently, Maine Public Service Company provides the first 300 feet for free and then charges $6.22 per foot. Our house location would be approximately 350-400 feet from the nearest utility pole, making it substantially cheaper than the first site.
Below is the proposed road. Its length is ~1,100 feet with a steep early decent from the main road, leveling off towards a stream and a gradual rise to the home site.
Below is the proposed utility line from my father's existing pole near his garage. Its length is ~370 feet.
One thing that has remained constant throughout our site determination is our home's orientation to take in the most sun possible during the winter months. 190-195 degrees is required for our south facing windows.
More on sun geometry coming up.
Sunday, November 11, 2012
Here comes the sun
The sun is the purest and most abundant form of renewable energy in the world. Ecoworld (2010) calculates that, "In full sun, you can safely assume about 100 watts of solar energy per square foot. If you assume 12 hours of sun per day, this equates to 438,000 watt-hours per square foot per year. Based on 27,878,400 square feet per square mile, sunlight bestows a whopping 12.2 trillion watt-hours per square mile per year." Whether that energy can be efficiently captured in a financially realistic way is the big question.
Although the power of the sun can be unreliable such as during overcast days, it is free, abundant and clean. It can provide unlimited home heating, limited domestic water heating and can be converted to DC electricity through solar electric panels to be used to run some or all of your homes AC electrical needs. The placement, size and type of solar electric/hot water system is a complicated one that takes into account latitude, sun angle, system cost, and electric demand of your home. Homebuilders can now justify building a home with solar electric and hot water as current federal and state tax incentives have never been better and prices for solar systems are consistently dropping (DSIRE). A typical system can now be paid off in as little as 8-12 years depending on the size and complexity of your system. Maine offers a up to $2K tax credit and a whopping 30% from the feds until 2016.
Electric solar generation can be utilized in two ways; grid-tied or off-grid applications. Being attached to the grid continues to be the least expensive and simplest system when using the sun for electricity generation. One avoids costly and still inefficient battery storage that also takes up considerable space in your home. One positive from off-grid systems is that if the power goes out, your batteries can provide you with electricity to run portions of your home. Most utility company's net metering cycle is yearly, allowing for a solar electric system to reverse your electric meter in the warm spring, summer and fall months when the electric load is small and the sun is "strong" (higher altitude), to offset and credit your bill from the electricity used in the winter months. Depending on your electric load and the size of your photovoltaic system, you could conceivably end the year not paying anything. With our utility company, our electric generation that is sold back to the grid only reverses your bill to zero, unable to receive money back in the form of credit or a check from your system's contribution.
Electric solar generation can be utilized in two ways; grid-tied or off-grid applications. Being attached to the grid continues to be the least expensive and simplest system when using the sun for electricity generation. One avoids costly and still inefficient battery storage that also takes up considerable space in your home. One positive from off-grid systems is that if the power goes out, your batteries can provide you with electricity to run portions of your home. Most utility company's net metering cycle is yearly, allowing for a solar electric system to reverse your electric meter in the warm spring, summer and fall months when the electric load is small and the sun is "strong" (higher altitude), to offset and credit your bill from the electricity used in the winter months. Depending on your electric load and the size of your photovoltaic system, you could conceivably end the year not paying anything. With our utility company, our electric generation that is sold back to the grid only reverses your bill to zero, unable to receive money back in the form of credit or a check from your system's contribution.
Saturday, November 3, 2012
Some important things to know
Although I was born and raised in Fort Kent, Maine, and experienced countless numbers of frigid winters and limited daylight hours, I was never concerned about how our home was kept warm and the financial and environmental cost associated with doing so. I was a child after all, not concerned with real-world problems and how they directly impacted me, my family and the environment. As I returned to Fort Kent to raise my family, I came face to face with the stark realization I was so oblivious to as a child; energy costs and their potential environmental impacts.
In 2007, my wife and one year-old boy moved into a large cape built in the 1940s; our first ever home. I had yet been responsible for paying for heat but soon found out the financial burden that comes with heating an old home in Fort Kent, Maine, climate. We had no choice but to conform to the norm of heating a home with oil. Our oil furnace was new in 2006 so we had that going for us but regardless of the heating source an older home will most certainly will have poor insulation and air infiltration leading to a greater heating load. This was our situation. We wanted a change towards greater efficiency and in a way that was environmentally responsible.
Grade #2 home heating oil is the most common heating source in Maine homes, heating a staggering 80% of Maine homes. UMaine Cooperative Extension Publications-2012 It's a fairly efficient, readily available and convenient heating source that is still abundant in Maine, throughout the United States and other developed countries. A huge infrastructure exists throughout our nation to provide customers with easy access to fuel oil and provide services to maintain simple and safe residential/commercial oil systems. Getting set up with oil is relatively inexpensive, with an oil furnace running nearly half of what a wood pellet boiler goes for, making it attractive for new home construction. Furnace efficiency standards are improving, as a decade ago, Mainers consumed 1,000 gallons per year and now are consuming approximately 850 gallons (worth noting that Maine mean low temperatures have been steadily on the rise in the past 10 years). Portland Press Herald-2011 One big problem with oil is its volatility in the energy market which makes it very unreliable in terms of price consistency, not to mention its general trend of its value to increase over time. Is is susceptible to supply and demand (as is any consumer product), natural disasters in even far reaches of the world (which are increasing in frequency, size and economic impact) wars and even forecasts and predictions on the trading floor. For example, historical data shows a dramatic rise in price since 1993 to the present (November 2012) when a gallon of #2 heating oil in Maine cost on average $0.85 per gallon and $3.84, respectively; a rise of ~450% in the last nine years (northern Maine prices are typically $0.15 more per gallon than the state average). U.S. Energy Independence Administration Despite this, Maine continues to be addicted to this form of energy with new homes surprisingly being outfitted with oil furnaces for their central heating means. Home owners are essentially locking into escalating/unpredictable energy costs for the life of their home not to mention using a non-renewable energy source.
Another common energy source used in Maine residences is firewood. Wood is now offered in a more convenient form including the increasing popularity of wood pellets with their high efficiency boilers and stoves. They produce greater BTUs per volume than their firewood counterpart and burn considerably cleaner, not to mention ease of delivery, storage, handling and cleaning. Home owners insurance premiums are higher in homes with wood-burning appliances as fires are a concern from creosote buildup in the chimney. It is typical to smell burning wood throughout our town and see a shroud of smoke blanketing the valleys during cold winter mornings.
Within the past several years coal has become another popular heating energy source as it is widely available, relatively inexpensive and provides superior BTUs per volume as compared to wood, pellets, heating oil, propane and natural gas. Carbon emissions are considerably higher than oil and wood, therefore it's not an acceptable green energy option.
Some sun/electric talk on the next post.
In 2007, my wife and one year-old boy moved into a large cape built in the 1940s; our first ever home. I had yet been responsible for paying for heat but soon found out the financial burden that comes with heating an old home in Fort Kent, Maine, climate. We had no choice but to conform to the norm of heating a home with oil. Our oil furnace was new in 2006 so we had that going for us but regardless of the heating source an older home will most certainly will have poor insulation and air infiltration leading to a greater heating load. This was our situation. We wanted a change towards greater efficiency and in a way that was environmentally responsible.
Grade #2 home heating oil is the most common heating source in Maine homes, heating a staggering 80% of Maine homes. UMaine Cooperative Extension Publications-2012 It's a fairly efficient, readily available and convenient heating source that is still abundant in Maine, throughout the United States and other developed countries. A huge infrastructure exists throughout our nation to provide customers with easy access to fuel oil and provide services to maintain simple and safe residential/commercial oil systems. Getting set up with oil is relatively inexpensive, with an oil furnace running nearly half of what a wood pellet boiler goes for, making it attractive for new home construction. Furnace efficiency standards are improving, as a decade ago, Mainers consumed 1,000 gallons per year and now are consuming approximately 850 gallons (worth noting that Maine mean low temperatures have been steadily on the rise in the past 10 years). Portland Press Herald-2011 One big problem with oil is its volatility in the energy market which makes it very unreliable in terms of price consistency, not to mention its general trend of its value to increase over time. Is is susceptible to supply and demand (as is any consumer product), natural disasters in even far reaches of the world (which are increasing in frequency, size and economic impact) wars and even forecasts and predictions on the trading floor. For example, historical data shows a dramatic rise in price since 1993 to the present (November 2012) when a gallon of #2 heating oil in Maine cost on average $0.85 per gallon and $3.84, respectively; a rise of ~450% in the last nine years (northern Maine prices are typically $0.15 more per gallon than the state average). U.S. Energy Independence Administration Despite this, Maine continues to be addicted to this form of energy with new homes surprisingly being outfitted with oil furnaces for their central heating means. Home owners are essentially locking into escalating/unpredictable energy costs for the life of their home not to mention using a non-renewable energy source.
Another common energy source used in Maine residences is firewood. Wood is now offered in a more convenient form including the increasing popularity of wood pellets with their high efficiency boilers and stoves. They produce greater BTUs per volume than their firewood counterpart and burn considerably cleaner, not to mention ease of delivery, storage, handling and cleaning. Home owners insurance premiums are higher in homes with wood-burning appliances as fires are a concern from creosote buildup in the chimney. It is typical to smell burning wood throughout our town and see a shroud of smoke blanketing the valleys during cold winter mornings.
Within the past several years coal has become another popular heating energy source as it is widely available, relatively inexpensive and provides superior BTUs per volume as compared to wood, pellets, heating oil, propane and natural gas. Carbon emissions are considerably higher than oil and wood, therefore it's not an acceptable green energy option.
Some sun/electric talk on the next post.
Thursday, November 1, 2012
Welcome
"It takes as much energy to wish as it does to plan." -Eleanor RooseveltOver the next 12+ months, join us as we plan, design and build a passive solar house that will redefine building practices in most extreme northern Maine.
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