Project Subtitle:
Project Description:
My wife, Mary, and I had long admired and wanted to live in a passive solar house similar to the one built in 1981 by our good friends, David and Harriet Borton. We replicated what they did with better materials and added solar produced electricity.
Our goals were to build a modest cost, high-performance, passive-active solar house that conformed to LEED Platinum standards and ran on site sunshine. We employed systems thinking and holistic design decisions to resolve conflicts that arose from the individual perspectives of architecture, beauty and aesthetics, building standards and codes, economics, energy and resource use, and environmentally appropriate construction.
We understood that design and material decisions rarely have one optimal choice, but rather, a preferred choice within the context of the particular project. Our overriding metric, however, was the lifecycle cost measured environmentally and economically with an inclination toward environmental lifecycle costs.
Our behaviors were, and continue to be, critical in making Trail Magic an energy and climate positive home (energy production exceeds energy use and the operation of the house and landscape result in a net reduction of atmospheric heat-trapping gases). We strive with varying degrees of success to use energy and resources only as required for the task at hand.
The detailed story of our project is given in Trail Magic: Creating a Positive Energy Home (Carl N. McDaniel, Sigel Press, 2012). Trail Magic's relevance and relation to similar houses and landscapes is considered in Durable Communities Emerge from Homes and Landscapes Powered by Sunshine, Carl N. McDaniel, Solutions, January-February 2014, Volume 5, Issue 1, www.thesolutionsjournal.org.
Building Type Summary:
Other Awards:
Lorain County Beautiful Award 2010 in environmental category.
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Occupancy Type and Details:
Owner-occupied. Both owners are living in the house and both are away about 15 days per year. We have guests (1 to 4 at a time) with a usual stay of 2 to 4 days. Guests are present about 30 days per year. The ground floor with two bedrooms, full bath, family room, and kitchenette was designed for guests.
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Multiple buildings?:
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Site description:
Site is located in Oberlin, OH, about 1 mile from town center that had 2 derelict houses that were raised and 60% recycled. Rectangular lot of 4.7 acres with 235 feet on south side of College Street that extends 840 feet south with the southeast corner located in Plum Creek. The center of College Street is 22 feet above Plum Creek. The new house is positioned 100 feet south of College Street and 35 feet from the eastern boundary. A 0.2 acre pond was dug south of the house to provide fill to raise the house site about 6 feet above grade, to be a heat source/sink for a heat pump, to grow fish, and for aesthetics. About 3 acres are field including about an acre of tall grass prairie with the remainder in woods with about half being in the Plum Creek flood plain.
Materials:
Local sources were sought and some recycled materials were used. For example: fill for raising house site ~6 feet came from digging a 0.2 acre, 12 feet deep pond; 16,759 board feet of site ash trees that would have been killed by the invasive emerald ash borer that had just arrived in Ohio and about a dozen other large trees were lumbered to provide flooring, shelves, book cases on stairwell wall, kitchen beam, front porch beams, pantry counter and shelves, closet shelves, dining table, and TV cart; recycled granite cobble stones were used for wood stove hearth; bathroom floor tiles were made from recycled material; front porch used recycled flag stones; and recycled stainless steel trays provided siding for wood bin in living room as well as the lining inside of a small ice box constructed under the counter in the ground floor kitchenette.
We elected to install a 24-gauge, standing-seam, metal roof instead of a standard shingle roof because it was made from ~75% recycled metal, would last for ~100 years with no or little maintenance, and could be recycled when removed despite the fact that the initial cost was 3 times that of asphalt shingles that would have to be replaced 3 times over ~100 years and the removed shingles would have to be put in a landfill. Prefinished, fiber-cement "Hardi-board" siding and trim were used for its durability, fire resistance, and low maintenance. High performance Loewen windows (triple pane on N, E, and W sides; double pane tuned for solar gain on S side) low-E argon with warm edge spacers were installed because of their exceptional quality and long life expectancy. Low volatile organic chemical paints were used on walls and ceiling, and water-based polyurethane on floors. Engineered rafters and joists were used in lieu of large dimensional lumber, which comes from old growth forests. Nothing larger than a 2 x 6 was used in construction.
Advanced framing techniques were used which minimized the amount of lumber needed without sacrificing structural integrity. Airtight construction of closed-cell spray foam along with extensive caulking and sealing, and high quality windows reduced significantly air infiltration (1.1 air exchanges at -50 Pascals). Insulation: under cement floor R = 20 (4 inches rigid insulation), ground floor half below ground with wall R = 35.5 (Reddi-Wall insulated concrete forms with additional 2.5 inches of wet-spray cellulose insulation, total thickness of 13 inches), first floor walls R = 47.5 (12 inch thick, double, 2 x 4 walls with 1 inch closed cell spray foam air barrier and 10 inches of wet-spray cellulose insulation), roof R = 62.5 (TJI rafters with 1 inch closed-cell spray foam air barrier and 15 inches of dense packed cellulose insulation).
Because of heavy clay soil that has zero percolation and in which garden vegetable plants grow poorly, we used grass mulch from our yard and fields as well as local tree chips and leaf-mulch soil to create organic soil for a 6,000 square foot garden. We acquired bare-rooted shrub and tree seedlings from Arbor Day donations and the local Soil and Water Conservation District to forest the front yard and reforest the flood plane areas from which we lumbered 16,759 board feet for the house and other projects.
We designed the landscape for water retention. A swale on the east side of the lot drains water away from the house through the tall grass prairie just east and south of the house and then down the meadow into the flood plane. A second swale on the west side of the lot drains water away from the house and from the garden into the pond. The pond is also fed by the overflow of a 1,850 gallon cistern that collects roof rainwater. We rehabilitated the flood plane area that had been a dumping ground for construction and other waste by removing or burying waste as well as by grading about half an acre to retain water before going into Plum Creek. We also planted tall grass prairie in 15 foot strips along the east and west sides of the garden, and a 10 foot strip around the pond. Tall grass prairie plants put roots down about 6 feet and some 65% of their photosynthetic product is put into roots thereby building soil water-retention capacity. The pond and tall grass prairie retain most or all of the water that falls on or flows into them.
LCA Description:
Our overriding metric in design and material decisions was the life-cycle cost measured environmentally and economically with environmental aspects given the edge. This is well illustrated in our choice of roof material. Our sandstone colored (reflective index of 63), 24-gauge, raised-seam, metal roof for the house cost $17,000 while a 25 year asphalt shingle roof would have cost $5,500. The metal roof was made from ~75% recycled steel, should last ~100 years with little maintenance, and is recyclable when removed. An asphalt shingle roof is a petroleum product that must be land filled when removed, requires some maintenance, and must be replaced every 25 years or so. Based on the initial economic cost, the asphalt shingle roof is clearly the best choice. Based on life-cycle economic cost the choice is unclear because three replacements of the shingle roof make its total cost ($16,500) similar to that of a metal roof over 100 years. Environmentally the metal roof bests the shingle roof in current and life-cycle costs. Giving the edge to environmental considerations made the metal roof the best choice. Of course, over 100 years future owners benefit economically from this decision while we and the wider society benefit now and in the future from this choice. Deciding to design for passive solar was easy: it cost nothing extra, or very little, while the life-cycle environmental and economic benefits accrue immediately. We attempted to make this life-cycle analysis on major design and material choices; however, we were often lacking sufficient data to do justice to many decision.
HERS Index:
Energy Star Score:
Annual renewable energy generated:
Electric Utility Company:
Gas Utility Company:
Datasets and Utility Bills sources and reliability:
Utility bill, utility meter, PV meters. Very reliable.
Electricity amount (imported from grid):
Electricity amount (credited or exported to grid):
Net electricity usage (purchased electricity):
Natural gas amount (purchased energy):
Energy Storage Capacity:
Energy Storage type:
The 2.10 kW PV system has 4, 1 kWh batteries
CHP Electrical Output:
CHP Thermal Output:
Subslab assembly:
4 inch concrete slab, over 4 inches rigid insulation, over vapor-air barrier, over ~8 inches of stone, over clay subsoil.
Slab edge assembly:
Slab edge (vertical description: 4 inch concrete slab, 4 inches rigid insulation, vapor-air barrier) down to clay subsoil abut directly on the polystyrene of the Reddi-Wall thereby closing vapor-air barrier around the house. One can start anywhere on the envelope and trace any cross section without encountering a break in the vapor-air barrier.
Foundation wall assembly:
Horizontal section going from outside to inside. Below ground: waterproof membrane on wall to concrete footer, 10 inch-wide Reddi-Wall insulated concrete form, 2.5 inches damp-spray cellulose, 0.5 inch gypsum board. Above ground: stucco finish over welded wire mesh, Tyvek rainwrap, 10 inch-wide Reddi-Wall insulated concrete form, 2.5 inches damp-spray cellulose, 0.5 inch gypsum board.
Above grade wall assembly:
Horizontal section going from outside to inside: fiber-cement siding and trim with Tyvek rainwrap on 1/2 inch OSB sheathing, 1 inch of 2-pound closed-cell spray foam vapor-air barrier, double 2 x 4 wall with precut staggered (as possible) studs, 11 inches of damp-spray cellulose insulation, 1/2 inch gypsum board.
Flat attic assembly:
N.A.
Cathedral ceiling assembly:
Cross section from outside to inside: 24-gauge raised-seam metal roof, 30# roof felt, 5/8 inch OSB sheathing, 16 inch engineered rafters with 1 inch of 2-pound closed-cell foam vapor-air barrier and 15 inches of dense packed cellulose, 5/8 inch gypsum board.
Door Area:
Space heating - Manufacturer & Model:
Space heating - capacity:
Space cooling - Manufacturer & Model:
Domestic hot water - Manufacturer & Model:
Ventilation - Manufacturer & Model:
Process:
Schematic design was created by Donald Watson, FAIA, who had been dean of architecture at Rensselaer Polytechnic Institute where I taught and who lives in Trumbull, CT. He asked us what our budget was and to describe in general the house we wanted him to design, the rooms to be in the house, how each room would be used, and the furniture to be in the room. We provided Watson with an owner's program that underwent 4 iterations, the first being 3 single spaced pages and the final version had 7 pages. We started with a rectangular house of two floors (3,600 sq. ft.), no basement or attic. Over 6 months he presented us with a sequence of floor plans that started with 2 floors and 3,000 sq. ft., and ended with 2 floors and a dormer totaling 2,500 sq. ft. (external dimensions). The schematic design was completed and handed off to Joe Ferut, a local architect in NE Ohio, who did the detailed design and oversaw the project.
Ferut with our assistance put Watson's schematic design plans out to 5 builders for bids. We were attempting to conform to LEED platinum standards although no builders in NE Ohio were LEED certified and the LEED homes program was in the pilot phase. One builder withdrew because he couldn't do the research to bid on a house conforming to LEED standards. Mike Strehle of All Seasons Builders, a small house building firm, wanted to learn about LEED and submitted the lowest and most thorough bid. Although he was only 31 years old, his quiet, calm, can-do personality made him an ideal team member for our innovative project. Our team had a talented, knowledgeable group that worked well with each other and subcontractors: Donald Watson, Joe Ferut, David Borton [PhD solar heat transfer physicist], Mike Strehle, my wife, and myself [PhD biologist]). Each member participated intimately in all aspects of the design and construction processes with the agreed upon goals of building a quality, high performance, passive-active solar house that would be positive-energy and climate-positive. This commitment was discussed with all sub-contractors who were encouraged to engage with achieving these goals.
Design for Adaptability:
Our goals were to build a house 1) of high performance that ran on sunshine and 2) of high quality that would require low maintenance and that would be sufficiently durable to be habitable for perhaps 100 years. Trail Magic had a 24-gauge raised-seam metal roof, prepainted Hardi Board siding, Loewen windows, extreme insulation (slab: R 20, ground floor walls: R 35.5, above ground walls: R 47.5, and roof: R 62.5), quartz kitchen counters, hardwood floors, hard wood bookcases and shelves, and other quality materials required for a long lived house.
Energy Modeling Software:
Joe Ferut and a building engineer ran heating and cooling models that were used to compare heating and cooling systems, and then for selecting the heat pump and determining the capacity of the pond loop.
Outcome of project goals:
Eight years of data on energy use and production as well data on water and hot water use definitively establish that we achieved a high performance home that runs on sunshine, has no energy bill, exports a significant amount of electricity to the grid, and is therefore a positive-energy and climate-positive home. The quality of living in a passive solar home is excellent, especially the quantity and quality of lighting, even during cloudy winters in NE Ohio.
We made one serious error. We should have made two heating and cooling zones. Zone 1, ground floor. Zone 2, first floor and dormer. For us it is not an issue except when we have guest in winter when that space needs to be heated making use of the wood stove not possible because the first floor and dormer get too hot.
We have had several equipment failures and replacements.
1. The programable thermostat failed and was replaced after 4 years.
2. The electric on-demand hot water heater had a design flaw that led to corrosion and failure of the control board. It was replaced after 7 years with a Stiebel, Tempra 20 B.
3. The evacuated tube solar hot water system proved to be inappropriate for domestic hot water heating because only 1% of the energy acquired was in the hot water used. It was removed after 2 years and replaced with a second PV system rated at 2.04 kW. The basic physics of hot water heating clearly establish this technology to be inappropriate for residential hot-water heating. Annually we use 2,500 gallons of hot water. The on-demand electric hot-water heater uses about 0.12 kWh/gallon to raise water temperature to 111 degrees F. Thus, 300 kWh are used per year for heating 2,500 gallons, or $30 at $0.10 per kWh. Even if 10 times this amount of hot water was used, the annual cost would only be $300. The evacuated tube system cost $6,500 while the on-demand hot water heater cost $800. Thus, heating hot water with an on-demand hot-water heater is 12% of the cost to heat with an evacuated-tube hot-water system.
4. The Carrier heat pump had a problem with heating after 6 years that required visits from the two service companies that installed the heat pump and the pond loop to correct the problem that apparently resulted from a design issue in the heat pump.
Discrepancies:
Yes, predicted energy performance of Trail Magic was better than estimated. We predicted, based on energy use in our previous house, that we would use ~3,200 kWh or 100% of the expected production from our existing 3.12 kW PV system. We were keen on using less than 3,200 kWh and were careful not to waste electricity. In the first year we used 2,279 kWh and made 3,192 kWh. We have added a plug-in Prius hybrid (~650 kWh/year) as well as replaced the evacuated tube hot water system with a second, 2.04 kW PV system. We also eased back a bit and now annually use ~3,300 kWh and produce ~5,200 kWh. Our local utility does not compensate for electricity sent to the grid, but they do not justify production and use annually. On November 1, 2016, we had 12,950 kWh in the local grid "energy bank" that can be used if needed in the future.
Total Cost of Project:
Construction hard cost:
Gross Cost of Renewable Energy System:
Value of Tax Credits for renewable energy systems:
Net Cost of renewable energy systems:
Cost breakdown info.:
Federal incentives:
Tax credits of $6,000 for PV system, evacuated tube domestic hot water system, pond loop and heat pump ($2,000 for each system).
State incentives:
No state incentives
Local incentives:
No local incentives
Utility incentives:
No utility incentives
Other incentives:
None
Annual Electric Savings:
Annual Revenue from SRECs or other renewable energy credits:
Advice:
The estimated pay back time for making Trail Magic a positive energy home is 17 years. Over 30 years the annual return would be 9% of investment. Not a bad return when one takes the long view. The estimated pay back time for the carbon of the embodied energy in materials and systems that make Trail Magic positive energy is a difficult calculation we are unable to do. However, based on the embodied energy pay back time for a standard PV system (between 4 and 8 years from estimates I've seen), it is likely to be less than 17 years.
It is also important to recognize that making your home positive energy is unlike other things you purchase for your house project -- it is an investment with a pay back time. Quartz counter tops, hot tubs, marble bathrooms, etc. are not investments with pay back times. At the same time, each is an expression of your values and ethics.
Another way think about the investment to make your home positive energy is to look at it as an annuity. However, unlike the standard annuity this "positive energy" annuity increases its payout over the years as non-solar energy costs increase.
Published References:
1. Trail Magic: Creating a Positive Energy Home, Carl N. McDaniel, Sigel Press, 2012.
2. Durable Communities Emerge from Homes and Landscapes Powered by Sunshine, Carl N. McDaniel, Solutions, January-February 2014, Volume 5, Issue 1, www.thesolutionsjournal.org
3. A youtube video on Trail Magic: www.youtube.com/watch?v=Y7Ax5vLVxQs (2013).
4. Achieving Climate-Positive, Energy-Positive Homes: 60 Years of Northeast Climate Housing, David Borton, Carl McDaniel, and Howard Stoner, Proceedings of ASME 2010 4th International Conference on Energy Sustainability, May 17-22, 2010, Phoenix, AR, ES2010-90075.
5. Creating a Positive Energy, Climate Positive Home Is Cost and Carbon Effective for New and Existing Homes, Carl N. McDaniel, David N. Borton, and Howard Stoner, Paper Presented at USSEE Conference: Building a Green Economy, MSU East Lansing, MI, 26-29 June 2011.
6. Evacuated Tube Solar Water Systems Are Not Energy Efficient or Cost Effective for Domestic Hot Water Heating in the Northeastern U.S. Climate, Carl N. McDaniel and David N. Borton, Paper presented at USSEE 2011 conference: Building a Green Economy at MSU, East Lansing, MI, June 26-29, 2011.
Special architectural measures:
Trail Magic employs the following special architectural measures: 1) Passive design window placement with 2.5-foot roof overhang on south side (63% of glazing on south side that is 6% of floor area; window area in square feet: north = 47, east = 24, west = 19; south = 155; total glazing = 245). 2) Thermal shades on larger east and west side windows to block sunshine in summer and reduce heat loss on winter nights. 3) A window halfway up stairs from ground floor to first floor daylights the landing and stairs going from ground floor to first floor. 4) Open risers on stairs from first floor to second floor dormer daylight front entrance and hallway. 5) Four small windows in kitchen just above counter tops daylight counter tops. 6) Sunset windows are high on west wall to daylight kitchen and dining/living room at the end of the day. 7) A sunrise window is high on the east wall that daylights east side dormer study and 1st floor bedroom in the early morning. 8) An Internal window between west side of the dormer study and the dining/living room daylights dormer study and visually connects the two spaces. 9) Stairwell with open risers on second flight of stairs and ventilation windows at high and low points in the house were designed as a wind tower to provide a fully ventilated house in warmer months, especially at night when cool air is drawn into the house on the ground floor and exists out the dormer windows. 10) The ground floor provides a summer refuge that is naturally cooler due to the thermal mass and earth berming.
Energy Strategies:
Passive solar design, evacuated tube solar hot water combined with on-demand electric hot water (as considered elsewhere, evacuated tube hot water system was a very poor choice and system was removed and replaced with a second PV system in Sept 2010), energy/water efficient appliances and technologies, and resident behavior of using what is needed and not wasting resources. By making our living space modest in size it is easy to conserve electricity because the radio in the kitchen is clearly heard in the living-dinning room, because reflective LED lighting of the kitchen and living-dinning room is accomplished with 80 watts, and because we only have two lamps in the living-dinning room area.
Energy Use and Production Documentation:
Subslab R-value:
Slab edge R-value:
Foundation wall R-value:
Above grade wall R-value:
Cathedral ceiling R-value:
Average window U-factor:
Solar Heat Gain Coefficient:
Visible Light Transmittance:
Door U-Factor:
Cost per square foot of Conditioned Space:
Air Changes per hour, ACH50:
Project Photos:
Number of Bathrooms:
Scope Description:
Trail Magic was built for Mary and Carl McDaniel, a retired couple, with the first floor and dormer being their living spaces. The ground floor was designed for guests with 2 bedrooms, full bath, family room, kitchenette, and a separate entrance from the south-facing, below-grade sun patio. Also on the ground floor are the mechanical and work rooms.
Site conditions:
Renewable Energy Sources:
Other Purchased Fuels Description:
No.
Storage Strategies & System Details:
The 2.10 kW PV system has 4, 1 kWh batteries
CHP Fuel Use:
Summary of enclosure strategy/description:
Air movement into and out of the house was reduced with an inch of 2-pound closed-cell spray foam from the peaks of the cathedral ceilings to the cap on the Reddi-Wall insulated concrete forms. The cap and Reddi-wall were caulked and sealed to the slab. A vapor-air barrier of a waterproof membrane was put under the slab. The goal was to reduce significantly the movement of air, and therefore heat and water, through and between the roof, walls, and floor.
Roof Assembly:
All roofs are hot above cathedral ceiling.
Roof R-value:
Window Description:
Lowen high performance windows. Triple pane, low-E argon with warm edge spacers on E, N, and W facades and Double pane low-E argon with warm edge spacers on S facade and tuned for solar gain and composite hard coat LO E.
Windows were custom made and each window had its own U factor, Solar Heat Gain Coefficient, and Visible Light Transmittance. Typical for N, E, and W. windows are U 0.22, SHGC 0.24, and VT 042. Typical for S windows are U 0.29, SHGC 0.39, and VT 048. Given below are averages of the typical values just given for N, E, and W windows and S windows.
Door Description:
Fiber glass with an R value of 8. When the outside temperature is around 10 degrees F, the inside of the door does not feel cool to the hand. We have 4 doors.
Number of Bedrooms:
Team Members:
Donald Watson FAIA, Earthrise, Trumbull, CT; EarthRise001@SBCglobal.net (Schematic Design)
Joseph Ferut, Ferut Architects, Vermillion, OH (detailed design architect and construction overseer)
Michael Strehle, All Seasons Builders, Lorain County, OH (builder)
David N. Borton, 7 Hilltop Road, Brunswick Hills, Troy, NY. (energy consultant)
Mary McDaniel, owner
Carl McDaniel, PhD biologists and owner.
Mechanical Equipment Installation Details and Comments:
Blower door