Sustainability – Test

Thinking about cost requires thinking about the lifespan of the building. Certain aspects of efficient building can be more expensive upfront, like triple-pane windows as opposed to double-pane. But, these choices result in savings over the life cycle of the project, conserving energy usage and adding value over time.

Typical construction methods often have a shorter-term outlook on a building project, while sustainable construction takes into consideration the longer horizon of the performance of a building. It requires that longer view to be able to design for less energy use, lower operating costs, and a reduced environmental impact over time.

For example, one of the priorities for energy efficiency in buildings is to keep heat (or conditioned air) inside. The envelope (that is, the outside of the building) is thoroughly sealed to prevent air infiltration and specially detailed to create thermal breaks, which are barriers that prevent energy loss. This often means that walls and windows are thicker to accommodate these layers. In recent years, the baseline construction methods that are considered “typical” are starting to incorporate or require these strategies (as in Massachusetts’ Stretch Energy Code), so what’s sustainable is now becoming what’s typical.

Most towns and cities in Massachusetts have adopted an energy code called the Stretch Code, which went into effect in January of 2023. It pertains to new buildings, as well as additions and renovations of a certain size, and it requires more energy-efficient building performance than the baseline national energy code (called the IECC, the International Energy Conservation Code). Compliance with the Stretch Code must be measured by the performance of the actual built home (see more about HERS ratings below), and our task as designers is to design the house to meet the performance target.

HERS stands for Home Energy Rating System; a HERS rating is a number that describes the energy expenditure of a home; the lower the number, the more efficient the home (zero being a zero-energy house). It is becoming more and more common to involve a HERS rater on projects to perform a suite of tests throughout construction to measure the efficiency of construction, resolve problem areas, and establish a performance baseline.

Thinking about durability means thinking about how a building will source its energy over time. “All-electric” buildings, as they’re called, use no fossil fuels onsite. That means all appliances, like the kitchen stove, are electric, and the way the building is heated and cooled must be too, like using a heat pump instead of a furnace. Ideally, a project could also produce its own electricity, using solar heat systems, photo-voltaic panels, or even small wind turbines.

• Ensure high-quality indoor air
• Design with daylighting in mind
• Use non-toxic materials
• Be environmentally sensitive
• Maintain consistent indoor air temperature

Conserve building materials

• Use materials that are sustainable, certified, contain recycled content, and have low embodied energy
• Buy local (materials that travel less than 300-500 miles) and use local craftsmen
• Recycle construction waste
• Don’t build bigger than it has to be

Conserve water

• Reduce the use of water with low-flow fixtures, hot water recirculation, high-efficiency sprinklers, and drip irrigation
• Reduce waste of water by separating gray and black water
• Capture rainwater and store in cisterns for irrigation

Conserve the land

• Protect and retain natural features
• Design the landscape for the place using appropriate plants and non-invasive species
• Build close to existing infrastructure like roads, sewer, and services

 

These acronyms stand for “heat recovery ventilation” and “energy recovery ventilation.” These are systems that provide fresh air to a tightly-sealed home (which is important for building efficiency), and at the same time recover energy from air at two different temperatures to reduce the heating or cooling load of a building. We incorporate these into the mechanical system of the house to make sure indoor air quality remains healthy and excellent.

There are many ways to think about what “lasts.” Ideally, our projects remain standing for a long time, so we use durable building materials, design with timeless aesthetics, and employ time-tested construction details to make that possible. But sometimes, what lasts is not desirable—like plastic in the ocean. Designing sustainably means being sensitive to both material use and material waste. This could mean renovating an existing home instead of tearing down and rebuilding. It could also mean salvaging waste from construction or demolition, in partnership with local organizations like GreenGoat. We advocate for these opportunities and conserving resources wherever possible.

One great example is the roof eave, which is the part of the roof that overhangs the outside walls of the building. It protects the walls from weather, which makes them last longer. We don’t build eaves in the same way as they were built in the 17^th century (we are more careful about thermal bridging now!), but we embed this strategy into our houses so they last longer as structures, and also so they fit appropriately within their historical context.