Going Green With A Timber Frame Home

We build timber frames only. But our clients have a number of options for finishing their timber frame buildings to be energy efficient and environmentally green.

Enclose and insulate with Structural Insulated Panels

Our insulated frames exceed new MA requirements for energy savings. The 2017 regs require a rating of no more than 3.0 ACH (air changes per hour). Our finished buildings are often rated under 1.0 ACH. Shown is a section of one of the panel products offered by Foard Panel.

• Most of our clients cover their timber frame with Structural Insulated Panels (SIPs) on the rafters and sidewalls of the building. These panels are foam insulation sandwiched between sheets of oriented strand board (OSB). We coordinate with the SIPs company of the client’s choice, but recommend Foard Panel.
•  “R-value” is the capacity of an insulating material to resist heat flow. For example, in MA the building code requires insulation to R-values of 18 for walls and 49 for roofs. We check local codes wherever we build. Foard SIPs can provide up to R-110 – depending on the type of panel chosen – to meet or surpass any building code in the US.
• The panel company applies SIPs to the outside of the frame, covering the sidewalls and roof completely. Therefore the panels provide a continuous air barrier and thermal envelope. This system also makes the handcrafted frame visible from the building’s interior.
• The OSB sheet on the exterior side of the building provides the base for clapboards or shingles; on the inside, sheets of blue board are applied to the OSB sheet, leaving the wall ready for plaster or paint. The SIPs system encloses the building quickly.

Other ways our timber frames go green

The panels on this timber frame farm building generate energy for the farm.

• Timber buildings last for generations.
• The frame’s joinery is wood-to-wood. This eliminates the need for metal fasteners or brackets.
• Timber frames accommodate solar glazing and energy-efficient windows and doors.
• Clients can choose air-source heating and cooling.
• A solar company can add Thermal/photovoltaic panels to the building to generate energy.

Note. Increasingly building codes call for houses to be tighter regarding air penetration through all potential openings in a building. One big hole in the envelope of a house is the chimney. In an otherwise airtight house, outside air may be drawn down chimney flues to provide the oxygen needed for combustion, resulting in heat loss and a sooty odor in the house.

If homeowners are planning on a fireplace or wood stove, they should work with a HVAC specialist and their mason to ensure that air is ducted in for their wood-burning device and that a heat-exchange device to conserve energy is part of the system. But be aware that multiple wood burners and multiple flues may be incompatible with an airtight house – and should not be necessary. An alternative is an air-source heat pump, which provides energy-efficient warmth. (See link above.) If a single stove or fireplace is desired, it must be carefully designed and installed.

 Reaching the highest standards

Most of the panels plus blueboard have gone up on the sidewall shown here. Later they will be painted or plastered.

• The Passive House Institute US (PHIUS) is committed to high energy performance. Their requirement for an airtight house is .6 ACH50 (Air Changes per Hour at 50 pascals of pressure). One of our timber frame buildings with SIPs received a HERS (Home Energy Rating System) rating of .25 ACH50.
• In a Net Zero building, the amount of energy used by the building annually equals the amount of renewable energy created on site. With a combination of SIPs, an air-source heat pump, and solar panels, our clients can have a Net Zero timber frame building.

An air source heat pump unit mounted on the wall.