Viridescent House/Office

Photos

credits: Trent Bell Photography, Cory Templeton, Revision Energy

Project Name

Viridescent House/Office

Maine’s First Net Positive Passive House

TideSmart Global is an experiential marketing company in Falmouth, Maine that is committed to investing in the future of its employees, its community, and the sustainability of the natural environment.  When it came time to replace a small residential structure on their campus, they wanted a new building that would meet the highest of energy efficiency standards (Passive House) and serve as an example for the building industry in Maine and beyond.

The result is a certified Passive House that generates far more than twice the energy it consumes, making it significantly net positive with zero emissions. This is achieved by dramatically reducing the building’s energy demand and installing copious amounts of renewable energy in the form of a 19.4 kW solar array that occupies the entire roof. This “extra” power is used to power a vehicle charging station (that is free for public use) and to offset power consumed by other existing buildings on TideSmart’s campus.

Viridescent’s design is founded on passive solar design principles, orienting the building and configuring the fenestration to maximize solar heat gain in the winter and minimize it in the summer.  It features a highly insulated and tightly-sealed exterior thermal envelope consisting of vapor-open Larsen truss walls (20” thick filled with dense-packed cellulose), a frost protected slab (8” of polished concrete over 10” of EPS insulation), European triple pane tilt turn windows, and detailed connections that are tenaciously sealed and thermally isolated from the exterior. It also features resource efficient, highly durable, low emitting materials, LED lighting, water efficient fixtures, an energy monitoring system.

Being located in a commercial zone, it was also important for this home to be flexible enough to be used as an office.   It is currently occupied by Tidesmart in this capacity, but with a few small modifications, it can easily be turned into a two bedroom house.

Its physical design is simple; a two story rectangular volume topped with a single shed roof who’s shape perfectly supports the solar panels that run from edge to edge. The volume is brought down to a human scale with a protrusion at the entrance.  Its roof blends into the canopy, the brise soleil, and the material division that bands the building.  Warm thermally modified poplar siding clads the building on the exterior of the first story where human interaction will take place. The siding is woven on the corners to create a sharp edge that expresses the grain and beauty of the material while maintaining a sharp edge that blends with the fiber cement panel siding above.

The building’s strongest feature is the corner window wall.  This is simultaneously the building’s primary heat source and its most sensory energizing feature.  It defines the interior atrium, fills the main living space with natural daylight, and creates a strong indoor/outdoor relationship for the occupants and visitors, filling them with a sense of comfort, and contentment.

Viridescent is a building mindful of its place on the planet, and its role as a steward for its occupants, neighbors, and generations to come.

SUMMARY OF DESIGN INNOVATIONS:

  • Passive House Design Standards
  • Substantial Renewables. Net Positive (19.4 kW array, generates far more than it consumes)
  • Vapor-open wall and roof assemblies: The truss wall construction and inverted roof assembly (sheathing on the inside) allow the home to be shell tested for air leakage easily and accurately in the early stages of construction. They also create a continuous layer that is simultaneously an air sealing layer and a class 1 vapor control layer that is located toward the interior (warm) side of the assembly.  From this layer outward, the assemblies are vapor open allowing them to dry rapidly increasing the home’s durability.
  • Frost protected 8” thick polished concrete slab provides substantial thermal mass while providing highly insulated contact with the ground.
  • Triple pane European tilt-turn windows (ug=0.088, SHGC=0.5) create tightly sealed, well insulated portals for natural daylight and solar energy.
  • Passive solar design (orientation, fenestration, thermal mass, and shading) provide the primary means of thermal comfort and financial efficacy.
  • Energy Modeling with WUFI Passive: Allowed the design team to fine tune the design as it progressed to maximize energy efficiency, durability, and efficacy.
  • Hygrothermic Modeling of assemblies (also with WUFI Passive) to study moisture migration through the wall assemblies to ensure resiliency and durability.
  • Tightly sealed and blower door tested. (0.54 ACH50)
  • An AirPohoda 90% efficient iERV (combination ERV and HRV) constantly and efficiently provides fresh air to the building occupants (roughly .3 air changes an hour) and monitors the supply and exhaust air’s humidity and temperature and continually balances their exchange within its core to optimize performance.
  • The iERV is outfitted with multiple MERV 13 air filters.
  • High efficiency Ductless Mini-split heat pumps for heating and cooling.
  • Water conserving plumbing fixtures (water sense and dual flush toilets)
  • 100% LED lighting
  • Viridescent features resource-efficient and non-toxic finishes, materials and products (i.e. zero VOC paints, UFF millwork and doors, torrified local hardwood siding, local FSC oak flooring finished with vinegar and steel wool or “black magic” and polywhey)
  • Performance Tested by RESNET, Zero Energy Homes, and PHIUS Rater
  • Energy Monitoring installed to monitor building’s performance and improve occupant behavior.

 

ENERGY FLOWS & ENERGY FUTURE

Viridescent is substantially net positive!  In time, it will not only offset its own carbon footprint (created by its construction), but it will shrink that of its neighbors. Below is a list of its performance statistics:

  • Energy demand has been substantially reduced to passive house levels.
  • Heating Demand: 4.73 kBtu(ft2yr)
  • Cooling Demand:  1.46 kBtu(ft2yr)
  • Heating Load: 4.21 Btu/hr./ft2
  • Cooling Load: 3.59 Btu/hr./ft2
  • Air Tightness: 0.54 ACH50, 0.02 cfm/ft2
  • Primary Energy: 31.2 kBtu(ft2yr)
  • Total Electricity demand: 2,270 kWh
  • Installed PV: 19.4 kW array, 24,877 kWh produced annually (estimated), 22,837 lbs of CO2 offset annually (estimated).
  • Energy Moded with WUFI Passive
  • Tightly sealed and blower door tested. (0.54 ACH50)

Architecture or A/E Firm Name

BRIBURN

Architect

Christopher Briley, CPHC, LEED-AP, AIA

Team

Chris Briley, Ryan Bilodeau, Steve Woods, Katie Woods, Tony Cowles, Rhonda Birkbeck

Consultants

Landscape Architect: Cowels Design Studio, Structural Engineering: L&L Engineering, Solar: Revision Energy, PHIUS Rater: Horizon Maine, Passive House Consultant: Edward Pais, Interirors: Birkbeck Design

Location

91 Johnson Rd. Falmouth, Maine, 04105

Client

TideSmart Global

General Contractor

R&G Bilodeau Carpentry and Electrical