OUR APPROACH TO SUSTAINABILITY
The intention we bring to each project is rooted in a deep desire to provide our clients long-lasting comfort and health while treading as lightly as possible on the earth. We seek to integrate a sensitive response to a building site with innovative building science and the use of natural materials, light-filled spaces and hand-crafted details. Each project is an opportunity to create a thoughtful, bespoke design that is both durable and resource-conscious.
The comfort we strive to produce for our clients relies on a shared commitment to a holistic design approach from the beginning. This commitment starts with a detailed outline of spatial requirements and relationships, a deliberate and thorough assessment of the site to document environmental forces as well as code constraints, and a clear definition of the energy performance goals and objectives of the project. By establishing and defining these parameters early in the design process, we can best decide how to optimize each building project most effectively.
Whether the project is a multi-bedroom residence in an extreme climate or a one-room writer’s studio, we apply the same rigor and purpose to identify the solution that best melds our distinct technical acumen with a nuanced approach to placemaking.
Because climate change is driven primarily by the burning of fossil fuels, “climate action” ultimately means keeping coal, oil, and gas in the ground. Builders, architects, and owners can accomplish this by reducing demand for fossil fuels through creating high performance buildings based on energy efficiency, conservation, and a shift to renewable energy.
What do we mean by high performance? According to the 2005 Energy Policy Act, a high performance building “integrates and optimizes … energy efficiency, durability, life-cycle performance, and occupant productivity.” For us, high performance essentially equates to deciding to invest more resources during design and construction to reduce the energy consumption of a building over its life-cycle. This choice has the added benefit of lower operating costs and – most important – increased comfort.
We feel that designing and constructing a building with serious attention given to energy efficiency is a moral imperative. However, since initial cost frequently is an overriding concern, as a general guide, we group our projects into three levels of performance:
1 | PERFORMANCE PLUS
By following some basic best practices (the “low hanging fruit” of high performance), we can help our clients easily exceed the energy-use targets of a standard code-built house while only marginally increasing the cost. Some of these tactics (such as proper solar orientation, continuous air sealing, and mechanical ventilation) while somewhat straightforward to implement, still require accurate attention to detail to achieve desired results.
2 | ADVANCED PERFORMANCE
This next level of performance incorporates all the basic best practices while implementing a more robust approach to the overall building assemblies. By using high levels of properly placed insulation, specialized mechanical systems, and energy-efficient windows, our projects can reduce energy consumption by more than 30%. This standard is often the best choice for budget-sensitive clients who also want to optimize the long-term costs and benefits of high performance. For projects in California, these homes will typically qualify for a substantial rebate from the California Advanced Homes Program.
3 | PASSIVE HOUSE
For the ultimate in high performance, we can design and build to the Passive House standard (see PHIUS, the Passive House Institute US for an in-depth history and description). While incorporating passive solar principles, a Passive House is not to be confused with the classic “mass and glass” approach popularized in the 1970s. Instead, a Passive House uses the highest levels of insulation, strategically placed thermal mass, rigorous air sealing, the best available energy-efficient windows, minimal thermal bridging, and energy-efficient mechanical systems to reduce energy consumption by as much as 85% (although this percentage will become less as the minimum code standards go up – a good thing). Some of the measures that we follow to achieve this standard may be less cost effective, but clients who seek to be “early adopters” pursue this standard nonetheless for the incomparable comfort it provides and to support the overall innovation of the high performance building movement. As certified Passive House consultants, we can pursue Passive House certification on behalf of our client, which ensures that the building does in fact meet the Passive House standard.
ZERO NET ENERGY
Any of the above high performance building approaches provide an excellent starting point to become a zero net energy project (ZNE). Zero Net Energy is achieved when the energy consumption of a project is equaled or exceeded by its on-site energy production (typically a photovoltaic array). While any project can theoretically be ZNE with a large enough photovoltaic array, we take the goal of ZNE as a serious challenge to find the most cost effective and resource efficient means to reduce the overall carbon footprint of a project. In the case of zero net energy, this means using one of the above high performance building approaches to ensure that the photovoltaic array is not any bigger than necessary achieve zero net energy.
To support a renewable energy grid, our projects typically employ an all-electric solution for heating and cooling and domestic hot water systems. We specify equipment that use heat pump technology to achieve efficiencies two to three times higher than gas or electric resistance equipment. Heat pumps use electricity to power a refrigeration cycle. The “pump” in this case is moving heat from where you don’t want to where you do.
A properly designed building assembly must effectively manage four primary environmental forces: heat, air, water and vapor.
Conductive heat loss is controlled through the use of a “super-insulation” strategy: insulation values as high as twice the code required amount provide permanent energy savings over the life of the building at a reasonable increase in project cost. The positioning of the insulation in relation to the framing is essential to properly control for vapor transmission (see below). The use of advanced framing techniques (wall studs spaced at 24” on-center instead of 16”) further reduces the effects of thermal bridging.
Controlling undesired air infiltration (outside air coming into the building) and exfiltration (inside air exiting) substantially reduces the heating and cooling loads of a building. Constructing an airtight assembly requires thoughtfully sealing every joint and seam of the structure. A blower door test is used at different stages of construction to verify this work. Heat recovery ventilation is used to manage indoor air quality while at the same time retaining the interior heat of the enclosure.
Resisting the entry of water into a building is the primary objective of any building assembly. Typically, a building employs a combination of layers to shield the structure from water: an exterior cladding that can either repel or wick moisture; a rainscreen cavity in conjunction with exterior insulation that can shed bulk water the penetrates the cladding; and a water-resistant barrier (i.e. house wrap) that prevents any liquid water from reaching the sheathing layer.
When we say that a building “needs to breath,” what we really mean is that a building enclosure needs to effectively manage the diffusion of vapor. Without proper diffusion or drying potential, vapor can get trapped and condense within the assembly - potentially causing rot and mold to form. In a typical assembly, the water-resistant barrier acts as the primary vapor control layer. Any vapor that accumulates in the assembly from interior activities (perspiration, cooking, bathing) can migrate through the assembly.