net zero energy

EHH week 01: about Eastside Harvest House

Welcome to Eastside Harvest House, a new home designed to harvest food, sun, and rain on site.

A Kirkland couple seeking to build their new home had three main criteria for their site: ample space for an edible garden, room for elderly parents to live comfortably and share their home, and enjoying a sweeping view of Lake Washington and the Olympic Mountains.  They found a 1 acre dream site in the heart of Kirkland, largely undeveloped, with sweeping views of lake and mountains to the west.  The house is a 5 minute walk to grocery stores, coffee shops, retail, and restaurants.  There is a bus stop right at the street with service every 15 minutes to Kirkland, Bellevue, or Seattle, enabling car-free living.

The site will boast an abundant 6500 square foot garden for the owners to grow their own fruits and vegetables.  Irrigation will be provided by a subsurface drip system to irrigate two dozen raised beds, a dozen fruit trees, and numerous edible berry bushes.  A basement root cellar will store the garden bounty and ample kitchen counter space will enable home canning in season for personal use or to give as homemade gifts.

This 3500 square foot single-family residence will be divided into two suites, each with its own kitchen.  The master suite will group the living, dining, and kitchen in one great room with a master bedroom and bath, a guest bedroom and bath, his and hers offices, and an exercise room.  The private in-law suite will have a smaller great room, with two bedrooms and one bath.

The floor plan allows for long term flexibility depending on the occupants.  The wall dividing the great rooms is structurally designed to allow connection as one single dwelling, perfect for a large family with the in law suite becoming the children’s wing.  But the wall can subsequently be divided again in the future to suit two smaller families.

The house will be one story over a full daylight basement to fit it into the gently sloping site.  An elegant stair will connect the two levels.  However, all the principal rooms in both suites are located on the main floor flush with driveway grade to allow for accessibility for elderly parents now, and the middle aged owners in the future.  Bathrooms are designed with aging in place in mind, with curb-less showers, comfort height toilets, and grab bars.

This house has ambitious ecological goals, targeting LEED for Homes Platinum and Built Green 5 Star certifications.  100% of stormwater will be captured and infiltrated on site in a 2200 cubic foot rain garden.  Rainwater from the metal roof will be collected in four cisterns in the basement totaling 12,000 gallons.  Filtration and UV sterilization will allow the homeowners to use the rainwater for potable purposes in addition to toilet flushing, laundry, and irrigation.  This is the first residence in King County to be permitted to drink its rainwater.  The project anticipates net zero energy, supplying 100% of its own power with a 17kW photovoltaic array and 30 evacuated solar hot water tubes.

The Eastside Harvest House is a truly functional, beautiful, and sustainable addition to the vibrant community of Kirkland.

Project statistics
Location: Kirkland, Washington
Lot size:  41019 square feet (almost 1 acre)
Number of units: 1 dwelling unit with attached mother in law suite
Total gross square footage: 4400 gross square feet (3570 conditioned)

Project Team
Client: (confidential)
Architect: VELOCIPEDE architects inc
Contractor: Model Remodel LLC
Civil engineer: springline design, LLC
Landscape architect: Outdoor Studio
Structural engineer: Harriott Smith Valentine Engineers, Inc.
Mechanical engineer: Ecotope, Inc.
Solar designer: Solterra Systems, Inc.
Surveyor: Pacific Geomatic Services, Inc.
Geotechnical engineer: Geotech Consultants, Inc.
Arborist: Urban Forestry Services, Inc.

 

EHH week 33: energy monitor

This house is aiming to be a net zero energy dwelling.  In order to reach that ambitious goal, the homeowners will need to carefully manage their energy usage throughout the course of the year.

 

Reading the main utility meter only tells the total electricity consumed.  But if it is running high, they need to know where exactly the power is going.  Is it the hair dryer?  Are the garage door openers on standby?

 

There are several inexpensive ($100) energy monitors on the market, which in my view are worth little more than saving a trip outside to read the meter on the wall.  There are also a number of fancy and expensive ($10,000) energy monitoring systems with flat screen displays and all sorts of information intended for the lobbies of office buildings or high schools. 

 

So I was delighted to turn up a small local company called Converged Green that provides an affordable device that can monitor every single circuit in the house and lets us customize how we log and display it.  Best of all, it only draws 5 watts of power so it does not waste energy saving energy!

 

The electricity is measured using current transducers (CTs), which are little metal donuts that encircle the hot wire of each circuit in the electrical panel.  Each piece of equipment (range hood, water heater, etc) has its own dedicated circuit anyway.  But we had to instruct the electrician to group lighting on lighting-only circuits so that we get pure readings for each category.

 

EHH week 20: air sealing

To build a net zero energy house it is essential to reduce air leakage to the bare minimum.  Doing so requires a comprehensive effort by the contractors to fill every gap between the heated inside and the outside.  Typical problem areas are at electrical outlets, light fixtures and switches, pipes and ducts, around windows and doors, and at wall intersections.  For this house, we used a combination of spray polyurethane foam and caulk to seal all these gaps.

 

During design, the architects determined the boundary of the air barrier surrounding the whole house.  At the walls and floor overhangs it is the plywood sheathing, which had all its joints covered with black butyl tape.  At the floor and foundation it is the concrete slab and walls.  And at the roof it is the sloped gypsum board ceiling, which had a dozen light fixtures hung from it that were enclosed in a special airtight plastic box.

 

To confirm air tightness, a device called a blower door is used to depressurize the interior to 50 pascals.  The blower fan is trying to suck outside air in, which can be felt by the test technician using a damp hand and an infrared camera.  A gap as small as that between two uneven pieces of wood is significant.

 

Our specs targeted 2.0 ACH50 (two air changes per hour at 50 pascals) as an ambitious maximum, but the team wanted to get much lower.  Our first blower door test achieved 1.6 ACH50, which is a terrific result.

Smart design begins here.