Net Zero?

Lily Pond House Solar Plant

It has been exactly a year since we moved to our Lily Pond House. So how did our passive and active solar design perform? How close did we get to our net zero goal where annual energy consumption is roughly equal to renewable energy generation?

Starting with the passive solar design with South facing wall of glass, every sunny day was a joy during winter. On those sunny days with freezing temperatures, we often had to open windows as the temperature reached about 78 degrees after the living room cement slab could no longer absorb the sun’s heat. If the cement slab was not covered with furniture and rugs, we could have stored more solar energy but life trumps energy efficiency. Radiant heating did not have to kick in about 3+ hours after sunset while the cement slab warmed the house releasing the stored heat.

One of the best decisions our HVAC contractor Jim Godbout Plumbing & Heating made at the suggestion of our solar contractor Revision Energy was to go with an all electric energy for the house. Daikin Altherma, air to water heat pump that provides low temperature hot water for radiant heating and radiators, proved to be an efficient workhouse. We didn’t have a single day laboring to heat the house thanks to Theodore and Theodore Architects high performance shell design with minimal thermal bridging. Having radiant heating in the living room and basement cement slab, and bathroom tiles also  helped the cause with heat retention.

For active solar, Revision Energy designed a ballasted system that does not require the installation to penetrate the roof, which is a plus. However, solar panels are then limited to 15 degree pitch because beyond that the wind load gets too high and the required ballast gets too heavy for roof support. Although the optimal angle for solar panels is about 40 degrees for our location, the total annual production is fairly insensitive to installation angle since we can bank excess production for 12 months by feeding the excess solar electricity  into the grid. This is because the lower installation angle is optimized for the summer months when the sun’s radiant energy is at its highest. The penalty for 15 degrees tilt is less than 8%. Low pitch installations also hold snow longer than steeper ones;however, the penalty for snow cover is about less than a 10% effect in southern Maine.

Revision Energy estimated our expected electricity consumption at 11 MWh per year:

Plug Loads: Design estimate was 450 kWh a month, or 5,400 kWh per year. Although it was on the low side for a 2,500 sq. ft. house, it was justified by all LED lighting and  energy efficient appliances.

Heat: Design estimate was 15,000 BTU/sq. ft. for the expected annual heat load. That translates into 38 MBTU/year for space heating, given the 2.5 Coefficient of Performance (COP) for Daikin Altherma heat pump  yields an expected electricity consumption of an additional 4,450 kWh per year.

Domestic Hot Water: Design estimate was 40 Gallons per Day (GPD) load with two occupants at 20 GPD each. That translates to an annual load of 10 MBTU/year. Given the 3.25 Energy Factor  performance of our Voltex Hybrid Electric Heat Pump  water heater, that translates to an additional electric load of 1,200 kWh per year.

11 MWh solar plant design called for 36 255 -Watt Canadian Solar photovoltaic panels. Unfortunately, our two roofs could only accommodate 27 panels. So we had to go with the more efficient 300 Watt LG NeON panels resulting in a 10 MWh per year power generation.

Best Month – May

Worst Month – January

Since roughly half of our total electric load is space heating, our electric consumption in winter is effectively supplied by our solar production in summer. Our best month was May with 50 kWh electricity production on sunny days while our worst month was January with 20 kWh electricity production on sunny days except when the panels were covered with snow, which was about 10 days. Since photovoltaic panels can capture scattered sunlight to create electricity, they generated electricity even on cloudy days.

Solar Electricity Production by Month

Revision Energy’s initial design employed Solectria PVI inverters, which convert the DC output of a photovoltaic (PV) solar panel into AC that can be fed into the electrical grid or used by house electrical network.  As the solar  crew was laying out the roof and moving panels around to accommodate the parapet, and roof obstacles (e.g. vent pipes), they felt there might be enough partial shading on this system so it would really benefit from a slightly more advanced inverter solution. At their suggestion, we went with a Solaredge system that combines a central string inverter in the basement with individual panel optimizers on the back of each individual panel to improve system performance, especially when part of the array is shaded. In contrast to a traditional inverter system where the partial shading of a panel typically results in the total loss of power from that panel in order to optimize the power of all panels in the same string, Solaredge recovers the partial power from the shaded panel. In addition, Solaredge provides module level monitoring and performance information, which is a pretty neat bonus.

Upper Roof Panels Performance

Solar system was designed to be a net generator in summer and net consumer in winter.  As the data shows, Lily Pond House Power Plant is a net generator roughly 5 months (May, June, July, August, September), a net consumer 5 months (November, December, January, February, March), and roughly balanced  in the transition months (April, October).

Generated vs. Consumed Electricity

So what is the bottom line? We consumed 11.5 MWh while the consumption estimate was 11MWh. So if we could generate 11 MWh per our original design, we would have a net zero home. We took a 10% hit due to roof constraints, and another 10% hit because 10 MWh solar design produced only 9 MWh, mostly due to parapet shading. At the end, we generated 9 MWh of solar electricity while we consumed 11.5MWh. For the 2.5 MWh shortfall, we paid $300, which we really can’t complain about given the environmental wellness, which encourages us to live in harmony with the Earth by taking action to protect it:

 

 

No WikiHouse

bench by Zoulamis

WikiHouse is an initiative started by a couple of British entrepreneurs who are trying to apply the success of open source software, and open source projects like Wikipedia to building homes. Designs for low-cost, high-performance, low-energy homes are shared, customized, printed using digital manufacturing techniques that employ 3D printers  and assembled. The designs are modular with each part numbered sequentially in the order it’s assembled in order to make it easy to assemble.

Here is a video that shows the assembly and disassembly of a WikiHouse frame. There are affordable 3D printers such as ShopBot, Marchant Dice and Blackfoot, which are basically computer controlled cutting machines. Another option is to use a CNC (Computer Numerical Machines) mill shop instead like FabHub or 100k Garages for 3D printing services. WikiHouse is a fascinating marriage of digital fabrication and open source technology.

Doug Ludwig tile work

Who knows maybe one day all homes will be built like a WikiHouse but Lily Pond House was certainly not built like one. While Lily Pond House made maximal use of mass production  – from I-Joists to IKEA cabinets, and from laminated veneer beams to ApplyPly hardwood plywood, these engineered components were all meticulously customized by master craftsman. Through the construction process, we grew to appreciate the value of craftsmanship in building a quality house with meticulous detail. We have observed that craftsmanship in building a home requires being passionate about your work, caring about the quality of the final product, paying attention to details, and experience. The attention to detail started with our architects – Steven Theodore, who paid just as much attention to selecting the right door stops as to designing the sunscreens for optimum winter passive solar gain, and summer shading; and Wiebke Theodore, who worked just as hard in selecting the right tiles matching the natural sunlight and as hard in aligning the horizontal lines of the living room features.

Bob with parapet railing

As popularized by Malcolm Gladwell in Outliers, it takes about 10,000 hours of practice to master a skill in any field from carpentry to music, and from basketball to programming. Assuming you get to spend twenty hours a week in a job on practicing your skill, that is about for ten years of experience. Our building team had multiple craftsman with longer years of experience. Spang Builders foreman Chad never met a house building problem that he couldn’t find a clever solution for. If something did go wrong, our foreman was there to redo it right. Who knew that applying the wood filler to nail holes after three coats of polyurethane and before the final coat was the best way to do it? Chad’s crew – Charles, Robert, Vladimir, Fedor, Timothy – showed their craftsmanship in installing interior trim, hardwood floors, doors and windows and exterior cedar siding and Ipe decking. It was fascinating to watch how Bob scribed our decks to granite rock formations, and installed hundreds of Ipe plugs to hide the screw holes after making them one at a time.

scribing deck to granite

It was fun to watch our framing contractor Mike Studley compute estimates in his head using empirical rules he developed over the years.  Anyone can paint but it is hard to replicate the quality of Drobish Brothers who can paint flawlessly without  taping. Jeff and Doug at Marcotte Electric were meticulous to the point of aligning the screw heads in every electrical outlet to pay homage to Frank Lloyd Wright. Our cabinet maker Greg Zoulamis customized several of the mass produced cabinetry, and crafted several gorgeous  ApplePly custom built-in’s based on our architect Wiebke’s design. Tile guru Doug Ludwig took his time to make sure the results matched not only our but his expectations. HVAC contractor Jim Godbout‘s Jeff and Tobie made sure that our plumbing and heating implementation was mechanical art. Our metalsmith Greg Mailing did a masterful job in crafting our stairs, railings, and floor to ceiling enclosure for firebox and television. C. O. Beck’s zinc siding not only looks gorgeous but will last 100 years with no maintenance. Amabile Brothers plaster came out so nice that we decided not to put any holes on our walls to hang our paintings instead opted for STAS picture hanging system.  Our architect/builder team chose S. Richer of Sanford for cement flatwork that produced a hard non-uniform floor for the living room and basement. It has been exactly a month since we moved in, and really appreciate our home built by multiple exceptional craftsman.

Doug the electrician unpacking Pirce 

our metalsmith Greg Mailing

Let there be lights

Thanks to Energy Star, Unites States is making its slow migration from the incandescent light bulb to LED lighting with an intermediate stop at CFL. Incandescent light bulb produces light with a wire filament heated with an electric current. In 1,880, the filament in Thomas Edison’s  incandescent light bulb lasted 1,200 hours while 95% of the energy went to producing heat instead of visible light. After 135 years, it still does the same wasteful thing. In contrast,  Compact Fluorescent Lighting (CFL) lasts 8,000 hours and produces the same amount of visible light with 25% of the energy expended by an incandescent light albeit with the necessity of mercury recycling. Light Emitting Diodes (LED) lighting lasts a whopping 50,000 hours and produces the same amount of visible light with only 10% of the energy expended by an incandescent light. As with every energy saving choice, the up front cost of an LED light is higher although the operating cost of an LED light is 10% of an incandescent light. The savings is not trivial as according U.S. Energy Information Administration lighting consumes 14% of the electricity in a typical American home.

Residential Electricity Usage

The Energy Independence and Security Act of 2007 (EISA) set energy efficiency standards for light bulbs. Under the new law, household light bulbs will use at least 27% less energy by 2014 for a similar lumen output. The standards are technology neutral, which means any type of bulb can be sold as long as it meets the efficiency requirements. In fact, a number of manufacturers met the law by replacing the filament in the Edison light bulb with a halogen element. Given the performance we are going after in the Lily Pond House, we set out to eliminate not only the incandescent and CFL light fixtures but also the Thomas Edison era screw sockets by ensuring only LED lights can be used throughout the house.

Lily Pond House lighting was designed by Wiebke Theodore with a valuable assist on lighting fixtures by Greg Day Lighting. In selecting fixtures, especially for recessed lights, Insulation Contact (IC) rated new construction housings are attached to the ceiling supports before the ceiling surface is installed. IC housings must be installed wherever insulation will be in direct contact with the housing. The housing needs to be Air Tight (AT), which means it will not allow air to escape into the ceiling, thus reducing both heating and cooling costs. Unless you take care, some of these IC units are huge, taking valuable insulation space. For the recessed lights, we considered WAC and twicebright, and chose twicebright because the WAC option with its 0.9 cu ft volume took more than 10 times the volume of the twicebright option that took only 0.08 cu ft:

WAC 0.9 cu. ft.

twicebright 0.08 cu. ft.

As with most green products, the origin of the space saving twicebright offering is from outside of USA. This company brings Scandinavian lighting innovations to the North American market. When you get rid of the Edison era screw base, you get the bi-pin base invented by Reginald Fessenden for the 1893 World’s Fair in Chicago.  The International Electrotechnical Commission (IEC) periodically updates the bi-pin standards. GU10 10 mm twist-lock bi-pin for the MR16 light bulb in twicebright fixture has been around since mid-2000s. As a historical note Westinghouse won the contract to wire the first electrified fair with Tesla’s Alternating Current (AC) against Thomas Edison’s Direct Current (DC), and invented the bi-pin base because Edison’s General Electric company refused to allow his patented screw-base bulbs to be used.

120 volts of AC line voltage needs to be transformed into 12V or 24V DC for LED lighting. There are two kinds of transformers for this purpose: Large and heavy Magnetic Low Voltage (MLV) transformers, and small and light Electronic Low Voltage (ELV) transformers that are typically enclosed in the lighting fixture rather than hidden somewhere by the electrician. Magnetic transformers generate a low frequency hum while electronic transformers are virtually silent. It is ironic that more and more of the electronic equipment and lighting in our homes (e.g. laptops, phones, LED lights, etc.) run on DC power while the electricity is distributed by AC, necessitating the distribution of dozens of AC/DC transformers around the house. As a case in point, our design called for dado StepLine LED lighting that fits into the thickness of drywall. However, its installation requires running wires to a remote transformer, a hassle after the plaster is done. So we ended up going with WAC LED200 that is an integrated design that fits into a standard junction box.

WAC LEDme Step Light

dado StepLine LED

For Lilly Pond House, we have about 3 dozen twicebright recessed lights (used mostly on interior ceilings so as not to interfere with the house envelope) each with its dedicated electronic transformer. What is the carbon footprint of that? Wouldn’t be better if we had a DC distribution system? It is coming. The data centers with banks of computers have been using this solution for some time. EMerge Alliance – open industry association is developing a 24V standard for DC power distribution in commercial buildings. There is a big push in boating industry for distributed DC electric distribution system that will also save weight by replacing the mechanical fuse boxes with solid state ones. So the future of residential wiring will most likely be two independent wiring systems – a low voltage (24V DC) system for electronic equipment, lighting, and DC powered small appliances and a high voltage (120V AC) system for major appliances but until then we have to deal with the transition headaches.

 

Rising from the rubble

On 4 Aug. 2014, we went to the site to witness the demolishing our cottage. While it took greenGoat about 4 weeks to meticulously deconstruct  the material to be recycled, it took only 2 hours for Spang Builders to demolish our home. It was painful to see our old cottage to get pulverized into a rubble. We knew that our house served its useful life, but letting it go was an emotional ordeal for us. Although most of our memories were outside the cottage – sitting in front in our Adirondack chairs sipping a glass of wine enjoying the sunshine ripples on the pond, watching our kids catch bass in the pond, tracking the wildlife scent around our property with Beyaz, enjoying lobster bakes with our friends, there were still a lot of memories tied to the inside of the cottage – enjoying the crackling fire in our old fireplace, listening to the rainfall on the pond at dinner, watching our kids spend countless hours with the play kitchen on the deck. So we couldn’t watch the end of the demolishing process, and left.

view from the front door before demolish

demolishing starts

living room and kitchen gone

entering into living room from deck

view from the front porch

Jenni’s room last seconds

Once the dust settled, we were surprised how fast the foundation footing and walls rose up. Since our house is pretty much on a ledge, the footing had to be several steps following the site topography. At the end, the foundation footing needed 20 steps. We attended the first pouring of the cement along with Steven and Wiebke by depositing the obligatory quarters in the foundation for everyone in the family. Compared to the cinder block foundation of the old cottage, our new home’s foundation footing is concrete anchored in the ledge and reinforced with rebar. It is fair it say that our new home’s foundation will outlive the age of the old cottage.

foundation footing forms

first foundation footing pour

6 of the 20 footing steps (West elevation)

For foundation walls, the subcontractor used cast-in-place concrete construction by setting up removable interlocking forms for the pouring of concrete foundation walls. Steel rebar was added to provide strength to the wall. Since some sections of the foundation wall is exposed by design, vibrators were used to remove air bubbles. We will be able to asses the effectiveness of this effort better once the footing is covered up at the bottom of the foundation walls with landscaping, and the top of the foundation walls are covered  with siding. Once the concrete was cured, the forms were removed, and for the first time we could see our new home shaping up.

anchoring the foundation wall on footing

foundation wall forms with rebar

vibrating poured concrete to remove bubbles

foundation wall – South elevation

foundation wall – West elevation

foundation wall – East elevation

greenGoat Deconstruction

There are two schools of thought for when to bring the builder into an architect designed residential construction project. The traditional way is to invite several selected builders to bid after the completion of Construction Documents. This approach ensures cost certainty for the project. At the recommendation of our architects, we went with an alternative approach and  invited selected builders to bid on the Schematic Design. This approach only generates a cost range but promotes an architect/builder team to develop a better quality product with greater efficiency by soliciting the builder’s experiential knowledge into the design process. Steven selected four highly recommended Southern Maine builders to bid on our project. After reviewing the bids, we visited builder portfolio homes to get a feel for fit and finish, and spoke with their references. It was hard to discern based on the build quality of the builder portfolio, or on their references as they were all excellent. Based on the enthusiasm for the project, cost range and proximity to our home, we decided to go with Spang Builders, who as it turns out, built our dock on Lily Pond over 25 years ago.

Once we decided to let our cottage go, we wanted to make sure that maximal amount of the materials got recycled for another useful life. In particular, we wanted the pine paneling, and maple floors to be recycled in addition to finding good homes for the old appliances. We first invited Habitat ReStore, which is a retail outlet that sells donated used building materials, appliances and furniture at reduced prices using the profits to support Habitat for Humanity home building projects. Since Habitat depends on volunteers, it was clear they could only recycle the appliances and paneling. We then invited Amy Bauman of greenGoat, which saves residential building materials typically destined for land fills and finds new projects that need those materials. I have been on the Board of greenGoat for the last 10 years, and consider Amy to be the most environmentally conscious person among my friends. Even her annual Board reports are printed on the back of architectural blueprints meticulously cut to letter paper size!

Ted removing floor

Master bedroom floor

Recycled flooring

Balsam Wool insulation

Living room

Open floor concept

Amy didn’t disappoint. She made an arrangement with Ted Whitesmith, who teaches English in Boston during the winter, to deconstruct our Maine cottage taking advantage of his summer vacation. As it turns out, Ted was building a cottage in Northern Maine. So he was able to repurpose any material not sold for his own cottage. We gave the keys to Ted after July 4h, and greenGoat was able to deconstruct by the end of July not only the maple floor boards and tongue and groove paneling but also interior floor joists, doors, windows, walls, ceilings, insulation, exterior walls, deck, shingles, slate patio and steps, and other items too many to list. Ted worked tirelessly to deconstruct as much of the cottage as possible while losing over 20 pounds during the process. Who knew we could have had an open floor plan with Cathedral ceilings in our old cottage:-) We only kept the granite fireplace mantle from the cottage thanks to an assist by Spang Builders. One of the most satisfying moment came when Amy shared the photo below showing our deck reborn in Northern Maine. The next step was the actual demolishing, which was a lot harder to take than we anticipated.

Cottage deck reborn

Selecting an Architect

Our cottage on Lily Pond has been our summer home for over 25 years. Margaret and I always wanted to build a contemporary house on this location blessed with spectacular views in a private setting. We also wanted our new home to be green – respecting its environment sort of off the grid without going overboard towards a German passive house.

Initially, we researched prebuilt contemporary high performance homes. Santa Monica based LivingHomes sets the state of the art on the West coast while Blu Homes does the same on the East coast. While these companies offer several customizable plans, it became clear to us that our home on a ledge from the ice age within the constraints of the shore land zoning made the prebuilt option not feasible.

LivingHomes RK2 Model

So we really needed an architect that can take advantage of the site’s southern exposure for passive solar but also can fit into the ledge dictated constraints while expanding allowed by the zoning laws. We knew that we would have no trouble finding green architects and builders after all Maine attracts environmentally conscious people. However, we were a bit apprehensive our unorthodox contemporary taste did not fit into the traditional Maine architecture.

We were pleasantly surprised that Maine is blessed with some outstanding  contemporary architects with green design portfolios that include Elliott + Elliott Architecture of Blue Hill, Theodore + Theodore Architects of Bath, Carol Wilson Architect of Falmouth, Van Dam Architecture and Design of Portland, Kaplan Thompson Architects of Portland, Briburn Studio of Portland, and Caleb Johnson Architects and Builders of Biddeford.

If you want to get a feel for the green contemporary architecture in Maine, check out the book Houses of Maine by Elliott + Elliott Architecture, Maine Modern: 50 Years of Contemporary Architecture in Maine exhibition, Green Architects’ Lounge edutainment podcast by Chris Briley of Briburn and Phil Kaplan of Kaplan Thompson.

Lily Pond House

Lily Pond

We started our architect selection process in the summer of 2013. We interviewed a number of the contemporary architects to understand their contemporary design philosophy, exterior and interior level of design services, experience with high performance building design, and coastal zoning, and their approach to collaboration with the builder. After visiting portfolio samples, and having them visit our home to get their initial impressions, we decided to go with Steven and Wiebke Theodore as Steven’s and  Wiebke’s taste, and their philosophy of design meshed with ours, and we felt at ease with their personality and collaborative style. It is just that once you see a home in an architect’s portfolio (Ledge House, Island House ) that you can imagine living in, you are less worried what the new design will look like. So the journey starts.

 

Going for Contemporary

This blog chronicles our journey in building a contemporary energy efficient home in Maine. We have been spending our summers in our cottage for the last 27 years. In 2014, my wife Margaret and I decided to take the plunge by selling our Massachusetts home, and settling in Maine to experience life as it should be for the whole year.

Over the years, while our tastes varied with the styles of the times, our preference for the modern minimalist design stayed constant. We still adore our Scandinavian furniture that we bought right after getting married, and fondly remember our stays in Copenhagen, Rome, Prague shopping for contemporary home furnishings, and living with the modern design in Istanbul.

Scandinavian Design dining room furniture – circa 1979

Deck View of our Conantum Home

We lived 20 years in this Carl Koch and Donald Gillespie designed contemporary in Conantum – a neighborhood of Concord, MA with about 100 contemporary homes nestled next to Sudbury River and Walden Pond. Conantum was the idea of MIT economics professor, Rupert McLaurin, who envisioned affordable cost housing for young couples. Carl Koch, an architect and also a MIT professor, planned the houses. Joseph Kelley, a local contractor, was the builder. Carl Koch spent some time after graduation in Sweden where  blended  clean Scandinavian design into his work . Our Conantum home is an example of Koch’s mid-century architecture design with multi levels and walls of glass that invite the outdoors in. For an excellent overview of Conantum homes, see Bill Janovitz’ tour of Conantum.

Conantum houses were designed when energy was too cheap to matter. Our house tripled its original size with architect Donald Gillespie before we bought it. We spent our 20 years upgrading the heating system into a distributed one, insulating just about the whole house, installing energy efficient doors and windows house while remodeling without destroying the character of the house. No matter what we did, it never could reach the ACH (Air Changes per Hour) specification of a Pretty Good House. So we wanted a high performance contemporary design for our next house. So in the summer of 2013, our journey started with looking for an architect who could turn our needs and wants into a buildable vision.