In conversation with net zero and near net zero homeowners, we quickly discovered that residential sustainability is cost-prohibitive. Our site forwards progress to net zero on and beyond its property in a few unique ways.
Mass timber (Oregon State University)
Passive House (Phius)
Dynamic glass (Oregon State University)
Passivhaus (also called Passive House) proposes a new standard for building energy efficiency by requiring almost no energy for heating and cooling. By emulating the following Passivhaus principles of design, townhome operating costs can be expected to fall by as much as 80%.1,2
Building envelope: eliminate thermal bridging with continuous insulation throughout the envelope; seal all enclosures to prevent infiltration of outside air and loss of conditioned air.
Windows and doors: use double- or triple-paned windows with high performance glazing and dynamic glass; implement shading strategies and window positioning to take advantage of daylighting to reduce lighting loads.
Heating/cooling: air-heat pump with a low-temperature heating system, high transfer grilles between rooms, and a high quality R50 continuous insulation layer to maximize heating/cooling energy efficiency.
We recommend additional specifications complemented by resident education on sustainable consumer behavior strategies (e.g. shifting usage to off-peak hours, turning off/unplugging appliances not in-use, washing clothes in cold water):
Cross laminated mass timber
LED lighting
Energy Star certified appliances and bathroom/ceiling fans
On-demand heat pump water heater
Induction stove and cookware
Efficient low-flow water fixtures
Net zero water
Definitions:
Dynamic glass limits unwanted heat gain in the summer while permitting passive heat gain in the winter. It also blocks 90% of solar radiation from passing through, reducing peak cooling load by 23%.
Cross laminated timber (CLT) is a lightweight, but very strong paneled wood that has superior fire, seismic, and thermal performance. Installation of CLT is quick, easy, and generates almost no waste onsite.
The site's proximity to a floodplain puts it in a strong position to implement net zero water. This means that the building would use on-site alternative water sources to supply all of the its water needs. We recommend that the building follow the DOE's mainstream design, as the department's ideal scenario would require residential wastewater treatment for which we are not adequately briefed to advocate.
Two standard townhomes would cost around $99/sf to construct in Ann Arbor. Rocky Mountain Institute's analysis puts the current cost of net zero energy homes at 1-8% greater than the conventional home. The actual cost depends on location, size, design features, and appliances installed. Passive House design principles narrow this net zero range to a 3-5% increase from standard cost estimates. This puts the middle-of-the-range cost to build our townhomes at $103/sf.³
Calculating in the floor plan and contractor and design fees, the total budget comes out to about $412,000.
This site has array output potential in surplus of what is needed to power the townhomes. The townhomes' rooftop solar will generate ~13,500 kWh/Year as a function of its flat square footage and access to an estimated 1200 hours of usable sunlight.⁴ The retrofitted warehouses avail significant square footage on top of the residential array, amounting to 365,000 kWh/Year.⁵ This is a low-end estimate, as annual power generation could be improved by 70,000-100,000 kWh using ray tracking technologies.
Based on standard residential demand figures for Ann Arbor, this leaves a baseline of 390,000 surplus kWh generated annually. Since Michigan has a deregulated energy market under the jurisdiction of Midwest Independent System Operator (MISO), the developer could effectively operate a small utility-scale solar farm and sell surplus power on the wholesale market. This proposes a reliable source of income that can help cover the upfront costs of going zero net energy and bridge the gap between affordable and market rates. To this end, we recommend that the developer establish an LLC, with the opportunity for resident buy-in after breakeven.
The Inflation Reduction Act offers federal tax credits for both new energy efficient home construction (45L) and retrofitted commercial buildings (179D). These financial incentives can alleviate the sustainability cost burden across the property with provisions applicable to the townhomes, community center, and the myceliation facility.
The recently expanded Investment (ITC) and Production (PTC) Tax Credits for solar could be utilized to reduce upfront and maintenance costs of the development. The project is eligible for an ITC of 30% towards the cost of the solar array, with the potential for an additional 10% savings if domestic materials are used. Since the development is also functioning as independent power producer, it is eligible for a PTC of 2.6 cents per kWh produced, using 2022 rates adjusted for inflation. On top of energy market revenue, the PTC would yield roughly $9750 annually.
Bulk-buy programs increase both the affordability and legibility of home energy efficiency, lowering financial and technical barriers to entry through resident savings and education. Programs like Ann Arbor Solarize connect communities to help them tap into their collective buying power by facilitating group buys to increase market penetration and save on the total cost of green energy solutions. The benefits ripple out across communities when residents share their positive experience, disseminate lessons learned, and encourage their neighbors to join the path to reducing their energy footprint.
Equitable Ann Arbor Land Trust: nonprofit group catalyzing development of equitable housing in Ann Arbor with a focus on affordability, creative placemaking, environmental sustainability, and mixed uses.
Office of Sustainability and Innovation: City office that has many passionate and knowledgeable advocates for a sustainable and just transition internally, but also a network of partners and contractors across the sustainable design, net zero energy, home electrification space.
Ann Arbor Solarize: solar bulk-buy program.
A2Zero Ambassadors: City-led program in which residents drive the work of a just transition through sustainability projects that are built by the community, for the community. A previous ambassador group designed and implemented a food forest in the Bryant community and would make for a great addition to the food forest team on this site.
Rocky Mountain Institute: clean energy nonprofit that is a current partner of the Office of Sustainability and Innovation.
Live Zero Waste: Ann-Arbor based nonprofit group that could support residential composting program and implement zero waste cooking instruction in the community kitchen.
Joe Trumpey and Susan Fancy: University of Michigan professors that are local net zero energy (or near-zero) homeowners.
Mycocycle: Chicago nonprofit leading myceliation projects.
Intelligent City: Vancouver housing startup introducing affordable mass timber and passive house design projects to Canada and the US.
Great Lakes Food Forest Abundance: Family-owned company helping communities in Michigan and Wisconsin design and install their own food forests.
Marie-laure Cruschi
Home electrification - Electrification eliminates harmful indoor and outdoor emissions for improved population and environmental health.
Net zero energy - Our townhomes are designed to use as little energy as possible. Adding in the solar array, the building creates surplus energy which can be recirculated back into the local grid.
Net zero water - Net zero water buildings provide a way to enact more conscious consumption of a life-sustaining natural resource. These buildings reduce water use, maximize alternative sources, and minimize wastewater discharge.
Circular economy - From minimizing construction waste, to residential composting and reduce-reuse-recycle-refuse education, to an innovative end-of-life facility onsite, our property acts intentionally as a micro-installation of circular economy.
Food forest - The various trees and plants we have chosen promise improvements in air and soil quality, biodiversity, and urban beautification.
Flood mitigation - Living in nature is different from living with nature. That the residential site neighbors a flood plain cannot be managed by zoning boundaries alone. For this reason, we chose flood-mitigating crops to populate the food forest so that it functions both as an agent of placemaking and an agent of site resilience.
Myceliation - Myceliation offers a path of reuse for some of the most toxic, difficult-to-breakdown materials. It has the potential to divert a significant waste flow from landfill and recirculate it as a renewable material.
Consumer education - Sustainable lifestyle is quite near impossible to enforce. Our project will support sustainability that endures through resident education at several nodes. The food forest and community kitchen also may act as sources of environmental and sustainability education.
Placemaking - Co-housing developments center participatory design to promote resident ownership of the built environment. Through relationship-building and pride-of-place, co-housing has reciprocal benefits for the sociocultural environment that inspired its design.
Affordable housing - Co-housing is affordable by design. In addition to building community, residents build collective financial capacity.
More inclusive Ann Arborite identity - Commuters face the social distance of dedicating their working life to a community that they leave once they clock out. Additional affordable housing in the city can lower the barrier of entry and reconcile this identity conflict.
Local food - The food forest provides direct and local access to fresh produce. As a public good, produce comes at the affordable price of being a contributing community member. The forest also offers a way to develop important preparedness skills, such as planting and growing, foraging, and plant-based food preparation.
Social cohesion - In the context of climate resilience, social cohesion changes from a luxury to a necessity. In the practice of collective ownership and relationship-building, co-housing builds resilient communities from the inside-out.
Agents of change - Membership in a sustainable living and learning community counteracts the negative effects of eco-anxiety through collective processing and action. Net zero energy homes thus not only reduce power used, but increase power within by emboldening residents to lean into the momentum of climate action.
Treeline trail - The food forest and community center add to the list of attractions to the Treeline trail. Together, they engage trail users with various amenities and opportunities to get involved onsite.
Affordable housing - Housing affordability has numerous economic benefits. To name a few, there is tax generation, opportunities for economic development, increased job retention and productivity, and the ability to address inequality.⁶
Energy market share - The combined solar array between the townhomes and retrofitted warehouses will produce an energy surplus of over 375,000 kWh/year, which the developer may sell on the wholesale energy market to help cover the upfront costs of net zero and bridge the gap between affordable and market rates.
New recycling economy - Mycocycle's method of myceliation "promotes a closed-loop supply chain, converting [hard-to-treat] carbon waste into a usable by-product." ⁷
Property values - Food forests have been shown to promote urban beautification and increase surrounding property values. In addition, the neighborhood will have convenient access to the site's community kitchen and events.
Green space without eco-gentrification - Since food forests carry a specific function and aren't characteristically trendy, they are able to add neighborhood green space without triggering eco-gentrification and economic displacement, like parks, greenways, and riverwalks have been known to do.
Unpaid m/paternal labor - In a co-household of two families, savings on unpaid m/paternal labor translates into over $10,500 annually, if the pair of co-housed families can save each other even 1/16 of time spent caretaking, whether by relieving duty for date nights or filling in gaps of overtime hours at the office.
Calculations: $16.54/hour (living wage) * 14 waking hours for a 7-year old child * 365 days/year = over $84,000 per single parent, per year, divided by 16 = $5,250 per family.
Cost of resilience - The flood-mitigating effect of the food forest acts as a preventative measure of cost-savings.
Creation of jobs - Jobs will be created onsite between construction, maintenance, myceliation facility operation, food forest upkeep, community center operation, and the street food stand.
Sources:
“We Offer Turn-Key Urban Housing as a Product.” Intelligent City, September 8, 2021. https://intelligent-city.com/urban-housing-product/.
“Passive Building Principles.” Passive Building Principles | Phius Passive Building Principles. Accessed September 22, 2022. https://www.phius.org/passive-building/what-passive-building/passive-building-principles.
“Residential Estimating.” Building Journal. Accessed September 27, 2022. https://www.buildingjournal.com/residential-estimating.html.
“Savings Estimator.” Project Sunroof. Google. Accessed September 25, 2022. https://sunroof.withgoogle.com/.
National Renewable Energy Laboratory, and US Department of Energy. PVWatts Calculator. Alliance for Sustainable Energy. Accessed September 25, 2022. https://pvwatts.nrel.gov/.
“The Impact of Housing Affordability on the Economy.” Habitat for Humanity. Accessed October 2, 2022. https://www.habitat.org/costofhome/housing-affordability-and-economy.
“Markets.” Mycocycle, February 16, 2021. https://mycocycle.com/markets/.