Viridescent

Photos

credits: Trent Bell Photography, Cory Templeton

Project Name

Viridescent

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 as an office, but with a few small modifications, it can easily be used as a two bedroom house.

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

MEASURE 1: DESIGN & INNOVATION

  • Passive House Design Standards
  • Substantial Renewables. Net Positive (19.4 kW array, generates far more than it consumes)
  • Vapor-open wall and roof assemblies.
  • Frost protected 8” thick polished concrete slab provides substantial thermal mass.
  • Triple pane European tilt-turn windows (u=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
  • Hygrothermic Modeling of assemblies (also with WUFI Passive) to ensure resiliency and durability.
  • Tightly sealed and tested. (0.54 ACH50)
  • 90% efficient iERV (combination ERV and HRV) to ensure a high level of indoor air quality while maintaining energy efficiency.
  • High efficiency Ductless Mini-split heat pumps.
  • 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

MEASURE 2: REGIONAL COMMUNITY DESIGN

  • Viridescent replaces a dilapidated home that was demolished.  That home was a nonconforming structure that resided in a commercial zone on TideSmart’s contiguous commercial property.
  • Demolished home components salvaged by Maine Building Materials Exchange (non profit that provides salvaged materials and incredibly low prices to qualified homeowners and builders)
  • Viridescent is designed to be either a house or an office (its current use) making it an excellent transitional structure between the two zones (residential and commercial).
  • The Project  team’s intention is to be a “good neighbor” and create a building that is exemplary of sustainable construction for both residential and light commercial applications.
  • The building provides an Electric Vehicle charging Station that is free to the public.

MEASURE 3: LAND USE & SITE ECOLOGY

  • Viridescent replaces a building that was uninhabitable. Its immediate impact on the site is therefore quite minimal.
  • It utilizes the same public sewer and water connections.
  • Storm water is managed on site through collection, sub grade percolation, and vegetated swales.
  • While some minor vegetation was removed, it was replaced with new drought-tolerant, indigenous plants and trees.
  • Great effort and care went into saving and protecting the 74 foot ash tree to the northeast as well as the existing vegetated buffer to the west.

MEASURE 4: BIOCLIMATIC DESIGN

  • Passive Solar Design. Oriented on an east-west axis to maximize solar exposure and is liberally fenestrated on its southern side to take advantage of the sun’s daily energy offerings.
  • The generous roof overhangs and a brise soleil were designed to block the high-angle summer sun while allowing lower-angled winter sun deep into the building.
  • Frost protected 8” thick polished concrete slab gives the building substantial thermal mass to mitigate the impact of the sometimes dramatic daily temperature swings our climate experiences.
  • The exterior envelope is substantially insulated (Slab R-50, Walls R-58, Roof R-84) and sealed to protect the interior from the bitter cold of our region’s harsh winters.

MEASURE 5: LIGHT & AIR

  • Passive solar design. It is not only good for energy performance but for natural daylighting.
  • Large European triple pane windows energize the space with ample natural daylight and allow the major work spaces to be well lit with only natural daylight even on the cloudiest of days.
  • The window’s tilt-turn feature allows the windows to be open at any time without obstructing circulation providing natural ventilation whenever the exterior environment is pleasing.
  • An AirPohoda iERV 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.
  • All products and finishes were chosen that do not contain urea formaldehyde or emit VOCs  such as zero VOC paints, UFF millwork and doors, local FSC oak flooring finished with vinegar and steel wool or “black magic” and polywhey, polished concrete floors)

MEASURE 6: WATER CYCLE

  • Plumbing fixtures are Water Sense labeled.
  • Dual flush toilet.
  • Storm water is managed on site through collection, sub grade percolation, and vegetated swales.

MEASURE 7: 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.
  • 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
  • Hygrothermic Modeling of assemblies (also with WUFI Passive) was performed to ensure resiliency and durability.
  • Tightly sealed and tested. (0.54 ACH50)
  • The vapor open assemblies and highly durable, low-maintenance finishes ensure that Viridescent will be a blessing rather than a burden to future occupants and owners.
  • A low-energy balanced ventilation system provides continuous fresh air with a 90% (approximated) energy recovery rate.
  • Viridescent is combustion free, making it a zero emissions building.

MEASURE 8: MATERIALS & CONSTRUCTION

  • Frost protected slab construction: Minimizes site disturbance, saves money on concrete and excavation and puts that money toward insulation/formwork.
  • Slab insulation/formwork is manufactured offsite, dramatically reducing waste (waste product gets immediately recycled and reused). They are cut from Type IX EPS polystyrene based on the Architect’s CAD files. They are assembled in place and also become the form work for the slab.
  • Vapor-Open Larsen Truss walls: The walls are first constructed as simple 2×4 stud walls with Zip System sheathing. The sheathing becomes both the primary air sealing layer and the vapor control layer (class II vapor retarder). Then 11 7/8” wood I-joists are fastened on the outside vertically and wrapped with a WRB that acts as the building’s secondary air control layer. The I joist cavity is filled with dense-packed cellulose (high recycled content, low embodied energy, low global warming impact, low emittance). Then a ventilation rain screen is installed followed by siding.
  •  Vapor-Open Roof Assembly: Mono Pitch 23” Deep Roof Trusses. Sheathing at bottom of trusses allowed the building to be pressure tested after insulation with the air control layer completely exposed so that any air leaks can be easily found and sealed. The Truss cavity is wrapped in a SIGA WRB (chosen for its strength and permeability) then completely filled with dense packed cellulose then. 2x Diagonal strapping creates structural retention for the cellulose, a ventilation space for the roof, and mounting structure for the installation of the metal roof that follows.
  • Sheathing layers are on the warm side of the assembly eliminating the risk of condensation and mildew for the life of the building.
  • 13,000 pounds of dense packed cellulose were installed in the building.  At these levels of insulation the choice of insulation with a minimal (and easily recovered) global warming impact was paramount.
  • The siding is rot and pest resistant torrified poplar (cooked at close to 500° F in an oxygen free environment to prevent ignition,making it rot and pest resistant)
  • “Black Magic” Flooring: White vinegar was placed in a 5 gallon bucket with steel wool and let to  steep for 48 hours it was then mopped onto the white oak to create the deep charcoal stain.  This was then sealed with a Poly whey coating.
  • The Polished Concrete 1st floor eliminates the need for more an additional flooring material.
  • Simplicity of design, especially form, kept the cost in check. Excluding site elements (landscaping, paving, accessibility ramp, ext. stairs, EV charger) the construction cost for the building was only $214 per square foot!

MEASURE 9: LONG TERM FLEXIBILITY AND ADAPTABILITY

  • Viridescent was designed to be either a house or an office (its current use).  This was due to its ambiguous classification (as a structure replacing a home in a commercial zone). As a result, the building’s future use could be incredibly varied.
  • It’s open plan could accommodate any number of future commercial activities.
  • With a few modifications, the building could be a home again (by creating bedrooms from the enclosed conference room and office, removing the kitchen wall and replacing it with an island, and removing the reception and creating an entrance and foyer).  There is already a laundry hook up installed.
  • It’s highly durable assemblies and finishes will provide a high level of performance well into the future and represent an investment in the next generation who will inherit the building and its design.

MEASURE 10: COLLECTIVE WISDOM & FEEDBACK LOOPS

  • A circuit by circuit energy monitoring system recently installed to provide both the owner and the design team with real time and historic data on energy usage.
  • The solar PV array also is equipped with a monitoring system and web portal so that real time and historic data on power generation is always available. This will allow the owners to visually see if there is ever a problem with the system and give them the ability to budget future solar savings.
  • Web portal for the iERV. This portal can control the iERV and can report its temperature and humidity data for both supply and exhaust air.
  • Key members of the owner’s staff have been trained on the operation of the mechanical systems, solar system, and energy monitoring.

MEASURE 11 (EXTRA CREDIT): BUILDING FUNCTIONS AS WELL OR BETTER THAN INTENDED

Viridescent WUFI Report-