Twisp, WA

Methow Multi-family

Passive House

Patano Studio developed this affordable housing concept for a housing trust located in the Methow Valley. The trust was looking for a plan that would be energy efficient, durable, safe, healthy, economical, designed to create a “sense of place,” and foster community amongst its neighbors. Additionally, they requested project be phased with the goal of building five affordable homes by the end of 2018. Eventually, the site is proposed to have 15 homes that are ADA ready or adaptable, and are a mix of 2-Bedroom/1 bath (<900ft2) and 3-Bedroom/1 bath (<1,100ft2) homes.

The phenomenal, walkable site, allowed for a maximum of 16 dwellings per acre. Given the growing regional demand for affordable housing and the trust’s tight budget – Patano Studio proposed a scheme that fulfills and exceeds all of their requested criteria. The studio proposed that the trust build groups of Passive House townhouses that would be organized along community gardens and green spaces. The erection of townhomes would reduce construction costs, increase the development capacity of the lot without exceeding 33% lot coverage, simplify meeting the demanding Passive House standard while maximizing community/open space.

The Passive House approach is defined by its rigorous energy efficiency standards ensuring occupant comfort, durability, and energy savings. While Passive House is relatively new in the United States it is currently being implemented across Europe in vast numbers of affordable and social housing developments with the potential of being de rigueur for all. It is a physics-based approach, rather than an ineffective checklist standard. It verifies that the building’s efficiency works comprehensively, and is backed by decades of building science.

The surface area-to-volume ratio of 1- and 2-story cottages is high, increasing both construction and energy costs. In order to meet the construction budget and provide a buoy against energy poverty in the face of climate change and rising energy costs, Patano Studio recommends that the townhouses meet the rigorous Passive House standard. Passive House is an ultra-low energy standard that far exceeds the Washington State Energy Code, and would ensure that the project meets the minimum requirements of the Evergreen checklist on the energy portion alone, even before adding renewables. This approach would also significantly increase durability for the life of the building. The reduction of thermal bridging and the superinsulated roof required to meet Passive House would prevent ice dams from forming on the roof. Which provides an additional strategy to reduce long term maintenance costs and ensure project durability.

The Passive House standard is achieved by addressing the following:

Thermal Bridge-Free Construction: Optimized structural connections, eliminating potential for mold growth and rot. Comfort Ventilation w/ Heat Recovery: Fresh, filtered, pre-heated air ensuring a high level of occupant comfort.

Airtight Construction: Measures to eliminate air leakage, reduce drafts, and ensure long term durability of the building. Thermal Insulation: Optimized insulation to reduce heat loss and ensure high levels of occupant comfort.

High Performance Windows: Triple pane windows reduce heat loss and air leakage, and condensation buildup.

By meeting the Passive House standard, heating costs for the 900 SF homes will be below $80 per year at present Okanogan PUD residential rates, and below $100 per year for the 1100 SF homes. Total energy costs anticipated for larger-sized unit would be under $280 per year (4,172 kWh * $0.06648/kWh), but this is dependent upon resident education and driven largely by plug loads. This means a 3kWh photovoltaic system would produce as much energy as consumed for the 900 SF homes, and a 4kWh photovoltaic system for the 1100 SF homes.