Green & Solar Cottage

The Green and Solar Cottage is the result of a challenge: build a tasteful compact home on a difficult piece of property, utilizing experience gathered during our 30+ years of residential and interior design. The result is a sustainable, green, solar home that uses traditional and state-of-the-art principles, costs no more than any well built home, and has very low monthly operating expenses. The rental of the home, aside from the seaside/country experience, provides a physical space where people can experience first hand what Green and Solar is and obtain knowledge of its comfort and cost.

Contact

Holly
greenandsolar@cox.net
401-662-0883

The property has a vernal pond that was created 25+ years ago when a previous owner of the property dug a hole for a foundation and never built a house. This hole filled with water over the years, birds, wildlife and plants moved in, and now it is considered a vernal pond as recognized by the Rhode Island Department of Environmental Management.

The purpose of building green is to work with nature, so instead of an obstacle, the pond has definitely become an asset. The cottage, with the help of a mahogany deck, faces south and overlooks this pond. Four birdhouses define each corner of the pond. Each birdhouse is a duplex and home to bluebirds, blue martins and sparrows. Last year all were occupied, rent free.

A rock ledge was retained on the property to rim the driveway and provide the center point for a small bed of roses, sedum and other plantings.

This home is Energy Star certified and has a very low load for heating and cooling. “Energy Star Certification” is a must on new construction. They do a very reliable heat loss calculation prior to construction and a blower door test at the end of construction third party verification which provides all for free.

SIP Panels (structurally insulated panels) were used for their inherent super-insulating properties, low air infiltration, the ease in which they are erected and their sustainability quality. The plant is near the site, the manufacturing process has a minimum impact on the earth and they recycled materials used in manufacturing. They cost no more than a standard framing system. This construction method dampens external noise and allows you to control air quality.

Heat Mass The first floor is a concrete slab that is insulated from the exterior and fitted with radiant pipes for radiant heating.There is also a thermal wall on the second floor that is fitted with radiant heat pipes and provides a thermal mass.

Siding and trim were selected for low to no maintenance.

Windows and Sliding Glass Door are Andersen for low maintenance and high performance.

Solar Domestic Hot Water (Thermal) The sun heats nontoxic fluid in a Collector (evacuated tubes) which sit on the roof. When the fluid in the collector is hotter then the temperature in the Storage Tank (as sensed by a controller), a pump station automatically starts up and transfers the heat to the tank. The tank has three functions: Gather the sun-heated water, store it and transfer this heat for domestic and space heating use. Well water comes into this tank at about 50 degrees. This water is heated by the sun for domestic use (showers, washing machine etc.) and is boosted when needed by a Demand Heater (electric). This demand heater monitors the temperature and only turns on when needed to boost water temperature to 120 degrees (cloudy, snowy days etc.). The KEY to this system is HEAT IT AS YOU NEED IT. The tank can be at a temperature varying from 85 to 160 degrees; so sometimes no auxiliary heat is needed and other times a few degrees must be added. In the summer the temperature in the tank is usually high enough to supply 120 degree showers constantly. The Sun usually supplies over 80% of the domestic hot water. The tank also has a coil to transfer heated water for space heating.

Solar Assisted Radiant Heat (Thermal) We have extended the Solar Domestic Hot Water System to provide heated water through exchanger coils in the storage tank to Radiant Coils in the insulated slab and Serpentine Coils in the second floor common wall. These heat masses then release heat slowly to the living space. This, too, has a Demand Heater (electric) that monitors temperature and boost the temperature when needed to 100 degrees. Radiant heat, when coupled with a well-built home, provides consistent, draft free, comfortable space heating. During the winter months the temperature in this home has been set at 68 degrees and has stayed at this temperature within one degree. It is anticipated that conservatively 30% of the radiant heat will be supplied by the Sun.

Quick Anecdote: a 7 inch x 7 inch ceramic cube heater was used to heat the whole house during the winter months of construction.

Photo Voltaic (Electric) The product is simple and basically consists of three components: PV panels (in this case 10 - 180 watt = 1800 watts), an Inverter (a box that changes Direct Current from the Sun to Alternating Current for household use; it also protects power from going back into the grid during power outages so that a utility repair person won’t get zapped) and disconnect switches to protect while working on the electrical system at the site.

The PV system is grid tied (connected to the electric utility company). What that means is that the energy produced by the sun is used to run the electrical needs of the home. If you don’t have enough sun power the utility company supplies you; if you have any excess, that electricity is pushed back into your utility company system. You are given a credit for this amount and in effect the utility company stores your excess electricity to be used nights or during cloudy days when the solar photo voltaic panels are not producing electricity. The PV system was installed to lessen grid dependancy. It is hoped that the home will be “Net Zero” (which means the solar PVs will supply all the electrical needs of the house).

The total building cost, which included well and septic system, was roughly $178 per square foot. The solar domestic hot water and heating system cost about half what a conventional system would be, around $10,000. In no case should it cost more then a conventional system. The PV system (Photo Voltaic) was installed taking advantage of a partial state grant. The system will probably end up costing about $10 per watt or $18,000. The grant will lessen the cost by about a third and there are tax credits available. We are expecting the utility bill to be extremely low and hoping to be “Net Zero”.

It is our opinion that the cost per watt is presently too expensive for normal use. This system should not cost this much. I believe the cost of the system is being kept artificially high and will come down in the near future. Let’s hope!

We are willing to share all our costs and sources to anyone interested.

Tours are available when the home is not occupied. Let your class explore the many features of the green and solar cottage.

A 12-year-old girl who toured the house won first prize in the science fair at her school. She used sun-powered LED lights in a doll house and made a mock Solar Domestic Hot Water System using a toilet a paper roll with a top painted red for a tank. That’s what this Cottage is all about!

We want you to know how it works and its pricing. You don’t have to turn any valves, the system works on its own. Spread the word!