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November 13, 2006
A premise of the Building America program is that high performance homes must be sustainable both environmentally and economically. EcoVillage Cleveland takes this premise to a new level. From location to lumber to lighting—energy efficiency, resource efficiency, and durability rule at EcoVillage Cleveland, but withou affordability. EcoVillage Cleveland is about local and individual sustainability.
Building A front elevation (above left); solar panels on Building A garage (above right)
- Twenty town homes, two- and three-story units that average 1,600 ft2 each
- High density urban infill with rapid transit access
- Quality extra living space on lower level
- Detailed plans and "green" specifications
- Ducts in conditioned space
- Controlled ventilation
- Detached garages
- High performance envelope, windows and HVAC
- Advanced framing; FSC-certified lumber and finished wood products
- Pervious concrete and salvaged brick pavers
- Extensive construction waste recycling—on and off site
Location and Layout
The urban infill site was chosen for EcoVillage in large part because it is within a 5-minute walk of a newly renovated rail station. Where formerly 10 single-family houses stood in disrepair, there will now be 20 state-of-the-art town homes. The 3-story units have stepped down, walk-in basements with natural light, thermal envelope, and layout ideal for a separate quality rental unit or extended family living. The 2-story units are slab-on-grade and esigned to be more accesible. Each of these design fearures give value to the owner, to the community, and to the environment.
Energy Efficiency and Occupant Comfort/Health
Building a home that costs little heat and cool that also safeguards its occupants requires integration of engineering and architecture. At EcoVillage, the wall assemblies, controlled mechanical ventilation, sealed combustion furnace and water heater, sealed ducts in conditioned space, interior finishes, and even detached garage work together to provide comfort and reduce the health hazards associated mold, soil gases (including radon), combustion byproducts, volatile organic compounds, and occupant activities. Do some of these features cost more initially? Yes, but some cost less, keeping high performance affordable.
Resource efficiency starts with use less—EcoVillage employs every advanced framing technique available. And the multi-family design inherently uses less materials at EcoVillage, as with most buildings, are wood and concrete. EcoVillage calls for Forest Stewardship Council (FSC)-certified lumber or salvaged wood fro everything from framing lumber to trim and cabinets. Concrete and concrete block at EcoVillage are specced for high content blast furnace slag or flyash, both waste materials that can replace up to 50% of teh very energy-intensive Portland cement used in concrete. Lastly, from land clearing to pakaging—wood, drywall, and cardboard waste will be recycled or processed for use on site. Once again, some of these features come with a small cost premium while others produce savings, making material efficiency overall economical.
When a home and its components are built for the long haul, maintenance costs are lower and the home maintains its value. The environment benefits from less use of material. Durability must be designed and engineered into a home. Foundation, wall and roof assemblies perform as finely-tuned systems that safeguard building components from degrading forces such as liquid water, water vapor, extreme temperatures, and ultra-violet light.
Quality is a three-legged stool involving design, materials and installation. You need all three to achieve superior quality. Quality gives you superior economic and environmental performance as well. At EcoVillage, quality is driven by highly detailed architectural drawings and construction details, and project specifications that include environmental considerations.
The drawings and construction details for the EcoVillage project run more than 60 pages. They include complete framing layout and detailed cross sections for every wall assembly (and there are many different types). The drawings were designed to be used at the job site by the site superintendent and all of the trades. The EcoVillage set of drawings is complemented by the project specifications. Throughout the project specs are specific references to building principles and detailed graphics from the Builder’s Guide to Cold Climates (Building Science Press Inc.). The general contractor and each subcontractor at EcoVillage will receive a copy of this Builder ’s Guide.
Foundation detail: Note the type and location of rigid insulation in terms of both thermal and moisture performance, the complete and continuous drainage details for bulk moisture and the air sealing details as the foundation meets the framing assemblies above.
Balcony detail: Although the roof lines of the main structures are relatively straightforward, there are complex cladding, flashing, and air sealing details for the second story proches and the bump-out column bay on Unit 1. Achieving superior energy efficiency and durability with these details requires detailed drawings for follow-through during construction.
Wall section: For each type of exterior wall cladding (and there are three—brick, stucco, and lap siding), the wall assembly is tuned in terms of maintenance of the drainage plane, back-venting of the cladding, air infiltration barrier, vapor retarding properties of materials, and thermal insulation employed. Each wall system is an integrated system controlling the movement of heat, moisture, and air.
How do you add new specs related to environmental performance and still get in the standard language contractors will need? Since we could not find specifications for resource-efficiency to “plug into” the EcoVillage Cleveland project — we wrote our own. To develop our own “green” specification language, we did draw on resources such as GreenSpec. This language was weaved into existing standard spec language. And wherever we could anticipate that obtaining or locating less-familiar materials could be a hardship for the contractor or sub, we included complete distributor/manufacturer information within the specs (see "EcoVillage Sample Spec Language").
It can be difficult to find the information you need for alternative materials and methods, or to convince contractors, distributors, and even building inspectors that they are acceptable or even preferable. Alternative materials are often unfamiliar to both suppliers and the trades, resulting in a price or labor premium, or both. FSC-certified lumber and high content slag/flyash concrete are two prime examples. But resources are available (see “Some Basics About Substituting Pozzolans for Portland Cement in Concrete”). And as more projects such as EcoVillage Cleveland forge the way, the learning curve and ready supply of materials for other builders and clients will improve.
In planning, design, and specifications, EcoVillage is set up to be an exemplary science-smart, green, affordable project. Detroit Shoreway project manager, Michael Bier puts it this way:
"The EcoVillage townhomes are proving to be a huge success. BSC has designed and DAS Construction has built a housing development like no other in Cleveland. BSC's energy-efficient, durable and attractive design has created a strong demand for the townhomes, which are 80% sold - before completion of construction. The Building America team of DSCDO, EcoCity Cleveland, DAS Construction, and BSC has demonstrated the value of green building while simultaneously invigorating one of Cleveland's aging inner-city neighborhoods."
And the real proof of the project's impact comes from townhome owner Frank Fitzgerald, an electrical engineer by training:
"I was initially drawn to the townhomes for their environmental design, energy efficiency, and the PV systems. But the homes are also appealing in design and comfortable to live in. Now if we could just build more versatility in, particularly in terms of electrical controls and systems..."
See the "EcoVillage Energy Analysis" for more information about energy savings.
BSI-025: The Passive House (Passivhaus) Standard—A comparison to other cold climate low-energy houses