Mercer Island Residence

Location:  Mercer Island, WA

Size/cost:  3,583 sf / $422,000 (construction complete summer 2012)

Description:  This project consists of two phases.  The first being a partial demolition of an existing home in poor condition and the construction of a 896 sf Accessory Dwelling Unit (ADU), while the remaining portion of the existing dilapidated home to be removed and replaced with a new 2,687 sf house in phase two.  The family of four will reside in the ADU while phase two is being constructed, eliminating the cost for renting elsewhere during construction and having additional income with the separate dwelling unit after the both phases are complete.  This project is currently in the schematic design process and will be seeking the phase one building permit in the fall of 2011.  Below are two sketches depicting possible representations of the entire project.

Passionate for strength and sustainability, the client desires a structure with an additional safety factor on-par with hospitals and other essential facilities built-in to withstand “the big one”– a severe earthquake– and the project is to be constructed to the German Passiv Haus standard of energy efficiency.  It will be built using Structurally Insulated Panels (SIPs) with an internal post-and-beam structure to minimize thermal bridging by having an uninterrupted thermal envelope of high R-value foam.  A structural engineer will be brought on-board to provide the necessary calculations and additional structural expertise.  High volume fly ash within the concrete monolithic slab will help offset the reduced amount of Portland cement used in standard concrete and responsible for 9% of the global CO2 emissions during its intensive refinement process.  Atypical materials to be used for their additional strength and other properties include basalt rebar (as opposed to standard billet steel) and magnesium oxide board (in lieu of gypsum wall board).  The project has a goal to exceed energy code by having a thermal envelope R-value 200% that of code, will precondition incoming fresh air to a Heat Recovery Ventilator (HRV) via earth tubes, collect rainwater in underground cisterns for domestic re-use, create its own electricity or a portion thereof via photovoltaic panels, and require only the waste heat of appliances and occupants to heat the home.  Special design considerations include a rooftop deck and herb garden, passive solar design, natural ventilation, graywater reuse, rain garden storm water treatment as yard features, urban agriculture, and minimizing the blockage of sun onto neighboring properties.  As the clients age, Universal Design addressing elder living is being incorporated by planning for a future elevator (currently stacked closets of proper size).