The Passive Solar House on Ash is a custom-designed passive solar residence with a focus on durable finishes as well as long-term operation and maintenance. Located in the City Limits and in the Wildland Urban Interface, the design and material choices exceed the requirements for the most extreme fire hazard zone designation.

The home has a rainwater harvesting system for domestic use that provides for all its water needs. This is a glass of rainwater!

The first step in the rainwater treatment process is the 500 gallon sediment tank where sediments settle out and debris are removed by this screen.

This 10,000 gallon storage tank has enough capacity to store water captured from intermittent rain events to carry the owners through times of little precipitation.

This three-stage filter system is made up of a 5 micron sediment filter, a carbon filter and a UV disinfection unit. The rainwater is ready to drink after this final treatment!

Dual flush toilets and other low flow fixtures reduce the demand on the rainwater harvesting system.

The building envelope of this home is rather unique. The 2 X 6 construction is filled with batt Roxul mineral wool insulation (R-30) with 3” of Roxul ComfortBoard rigid stone wool (R-12) installed on top of the roof and wall sheathing.

This Henry Blueskin VP-100 peel-n-stick system was installed on top of the rigid insulation. It eliminates air leakage while functioning as a water-resistant barrier and rain barrier.

Following the waterproof membrane, sleepers were installed that create a 2-3/4” air gap between the membrane and the Core Ten metal roofing and siding. The gap creates a "cold" roof and walls which makes the home more impervious to fire.

Roxul mineral wool in this "advanced framed" wall. Advanced framing spreads the studs further apart than in standard construction, increasing insulation and decreasing heat transfer across studs (which is prevented on this project with a rigid insulation on the exterior).

This home also has a passive radon ventilation system, made up of perforated pipe in an air-permeable gravel layer beneath this rigid insulation. Flagstaff has areas with radon levels that exceed the recommend maximum levels of 4 picocuries per liter, so it is worthwhile to make the small investment needed for radon-resistant construction.

The insulation joints were taped and any penetrations were sealed with foam.

A vapor barrier was installed on top of the rigid insulation to further seal the slab from intrusion by radon, water vapor and other gases.

With a home as air-tight as this one, mechanical ventilation is recommended to ensure adequate air exchange with the outside. This fantech Heat Recovery Ventilator (HRV) will provide fresh air in an energy-efficient manner.

This Lochinvar high-efficiency boiler supplies hot water to heat the home through the in-floor hydronic system as well as for domestic use.

Attention was also given to selection of materials. This spruce lap siding used for the ceiling was from a reject pile at a local hardwood distributor.

The Sierra Pacific windows installed in the home were made with Sustainable Forestry Initiative-certified wood.

Composite material like this one are often made with reclaimed or rapidly renewable materials.

Construction waste reduction is difficult in Flagstaff. Great efforts were made on this project to divert as many materials as possible from the landfill. 40% of the waste in Flagstaff's Cinder Lake Landfill is construction waste and the City of Flagstaff is strategizing ways to reduce it as part of its goal of zero waste by 2050.