Aro Homes

2024 Design Awards Merit Recipient

Aro Homes are climate-friendly, ultra-low carbon, and better than net-zero homes intended to replace aging housing stock. Designed to be versatile and repeatable across a wide range of project sites and locations, the Aro Homes utilize a hybrid off-site / modular construction model, like the Sears kit homes, while appealing to a diverse range of potential buyers.

Sustainability and performance drove every aspect of the Aro Homes’ design. A range of strategies support reduced consumption of energy and water, including photovoltaic panels on the roof, plumbing to facilitate gray water reclamation and reuse, and power storage and management system in the garage. Intensive study of materials and construction tactics resulted in a reduction in the homes’ embodied carbon footprint, with carbon neutrality achieved in about 18 years.

An emphasis on high-quality, natural, and long-lasting materials underscore the design’s performance goals, resulting in a durable and resilient home that will last. Through each Aro Home, floor plans are adaptable, allowing room uses to be modified and change over time. Spaces typically reserved for storage are compressed; a 1.5-stall garage with electric vehicle charging acknowledges cultural shifts in car-usage to eliminate unnecessary space and accommodate future use.

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A solution for a modular house that doesn’t look modular. It integrates a quite contemporary interior with an exterior in a form that’s more familiar to most people, and probably fits into most neighborhoods in a in a more sympathetic way than what we typically see with a lot of modern modular housing.

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Measure 1: Design for Integration

Performance informed by data analysis was a major driver for the design. The Aro Homes achieve better than net zero energy performance by first reducing their energy consumption through a high-performing building envelope and high-efficiency HVAC and lighting systems. Deep study resulted in a roof orientation that offers PV solar exposure from almost any placement orientation on any site; each home is designed to accommodate an 8.7 kW PV array that can produce more energy than the home uses in a year – enough to offset its initial embodied carbon footprint in 18 years. Homes have an option for gray water reclamation and reuse, which further reduces water use by 50% as compared to the standard home.

As a repeatable design intended for markets across the United States, thoughtful siting was at the core of the project’s approach. it was critical that the house always achieve better than net zero energy performance regardless of the orientation. Deep study resulted in an L-shaped roof that allows for sufficient photovoltaic energy generation from any placement orientation on site—a core component in the 18-year carbon neutrality goal for each home.

Measure 2: Design for Equitable Communities

The Aro Home’s ability to set and meet high-performance goals ultimately serves everyone in the surrounding community and nudges the industry as a whole in a new, better direction. The shortened construction timeline likewise minimizes disruption within the neighborhood while filling gaps in existing communities, rather than contributing to urban sprawl. This infill model can be applied to many different kinds of housing types, ultimately reducing barriers to housing access as Aro Homes continues to refine and reimagine how to build efficiently.

Measure 3: Design for Ecosystems

Each Aro Home represents a comprehensive view of the local ecosystem, extending beyond the site boundaries to support healthy neighborhoods and cities. At each home, approximately 75% of the landscape is native and/or drought resistant. To preserve nighttime darkness, exterior lighting faces down and the wider lighting system is strictly controlled via timer.

Measure 4: Design for Water

As an option to buyers, every Aro Home is plumbed to allow for a Hydroloop gray water treatment system, which can be used for irrigation or toilet flushing. This can reduce water use 50% over a traditional home—especially important in a state like California, which is profoundly affected by drought. While the homes are not Water Sense certified, many sanitary fixtures do have this certification. Aro Home 4 and beyond will have a smart water use monitor that notifies the homeowner of potential leaks or high water use and can shut off the domestic water system.

Measure 5: Design for Economy

As the model becomes more efficient, costs for Aro Homes continue to decrease; the third house reduced costs over House 1 by more than 30%. Ultimately, Aro is targeting a cost at 25% less than comparable products, without compromising quality. Aro’s hybrid construction approach could be applied to other residential typologies, such as infill backyard housing and townhouse developments. The intent is to address issues of housing affordability in even the densest of regions—making high-quality design and high-performing buildings accessible to a diverse demographic of homebuyers across geographic markets.

Measure 6: Design for Energy

This all-electric, extremely energy efficient home has a predicted EUI of 13.0 kBTU/SF/yr (17% better than code) and PV panels that will produce around 13,909 kWh/yr—an excess of almost 2,500 kWh per year, offsetting over half a ton of CO2 equivalent from the grid (based on 2021 eGRID data). The L-shaped roof allows the house to be rotated to suit any orientation on any site without sacrificing PV energy generation. Since January 1, the home has produced 794 kWh more electricity than used, and is on track to meet its ambitious predicted energy targets.

Measure 7: Design for Well-Being

Though the homes do not target any specific chemical reduction, a base design directive was to limit toxicity. Aro Homes estimates about 75% of materials used in their homes are declare labeled or otherwise transparently / green certified. The mechanical ventilation system exceeds California Mechanical Code requirements, improving indoor air quality. A percent time controller is included in the home, allowing the homeowner to adjust the amount of mechanical ventilation they use (or to shut it off during times of poor outdoor air quality (such as during fire season).

Measure 8: Design for Resources

Initially, the homes were designed with a mat foundation, which would have required 56.3 years to achieve carbon neutrality. After LCA analysis via Tally, adjusted design to stem foundation, which significantly reduces the embodied carbon footprint of the home and reduces time to carbon neutrality to just 18 years. Over the lifespan of the building, it will offset more carbon than it uses, even taking into consideration the end-of-life carbon bump. Key carbon strategies include reduction in materials, reduction in foundation concrete, reduction in glazing, use of low-carbon cladding, recycled content in the steel and concrete used, and low-carbon insulation.

Measure 9: Design for Change

The design considers the impact of additional environmental/social risks, integrating a PV system with battery in case of grid instability and power outages. The home’s novel construction assembly approach makes the entire system very modifiable. The Aro Homes are “four square” houses, with simple rooms that can use used in different ways (such as offices transforming to bedrooms), while supporting single-level living to foster multi-generational families and aging in place. Flexible interior floor plans anticipate to the needs and lifestyle of a range of future residents.

Measure 10: Design for Discovery

Five Aro Homes are built or under construction across the Bay Area. Efficiencies and improvements include: integrating the roof with upper modules to eliminate added shipping and crane time; installing windows at the plant; and improved connection details, clustering MEPF and structural connections in limited access areas. Most modular products are wrapped in vinyl, which is thrown away; Aro has invested in reusable transport wrapping. POEs are planned for the first two homes, and buyer satisfaction is tracker across homes and warranty items. Aro remains actively involved with homeowners to capture data and improve future homes.