2012 Challenge Participant:
Applicants: Nick Lehto - Builder, David and Susan Griffiths - Homeowner
Project Address: Killingly, CT
Bdrms./Sq. Footage: 3 BD - 2,600 sq ft
This 2,600 square foot, single level home located in Killingly, is the future residence of David and Susan Griffiths. The lot is located on the Griffiths family farm and is currently home to grazing dairy cows. Since the farm has been in the Griffiths family for generations, they wanted to build something that would leave their “mark” on the land and be as energy efficient as possible due to the continual rise in energy prices. The Griffiths came to Lehto Design/Build with a plan designed by Brian Eicholtz of I Design Group called "the red cottage". Lehto Design/ Build reviewed the plans and incorporated to not only maximize solar orientation, but to also enhance surface to volume ratio to make for an overall more efficient shape. In addition, they implemented several features that make this house a contender to be a zero energy home.
Orientation and Envelope:
The home is built to a level of airtight construction that not only helps reduce energy losses but is also important to the structure’s durability.
- Walls: 12” double stud wall with dense packed cellulose for an overall R-45
- Sloped Ceiling: 18” Dense packed cellulose for an overall R-68
- Basement Walls: Insulated Concrete Form (ICF) foundation for an overall R-22
- Slab Insulation: 2” Rigid foam board for an overall R-10
To avoid thermal bridging, framing techniques used do not allow any direct wood connection between the interior and exterior. In a typical wood framed wall, every section of framing is a thermal bridge. These thermal bridges can account for as much as 20% of the overall wall area which dramatically reduces the overall R-value of the building envelope.
High efficiency triple pane windows are used throughout the house, with U Values ranging from .17 to .18, which equates to approximately R-5 to R-6.
Heating, Cooling, and Hot Water:
There are two air source heat pumps (ASHP) installed for the small heating and cooling load. An evacuator tube solar thermal system will be used in conjunction with a heat pump water heater for domestic hot water heating.
The home features a balanced energy recovery ventilation (ERV) system that is constantly supplying fresh air to living areas and removing unwanted stale air from areas such as the kitchen and bathrooms. This ventilation system recovers up to 94% of the heat from the house and use it to heat the fresh air entering. This constant supply of fresh air prevents the buildup of moisture and harmful contaminants.
In order to reduce electrical demand, all lighting will be low wattage CFLs or LEDs, and all appliances will be ENERGY STAR rated.
The home will use a 8kW grid-tied photovoltaic (PV) system to offset the homes electric usage. This system is sized to bring this home to net zero. In addition, the home will use an evacuator tube solar system to heat the home’s domestic water.