Sustainability is integral to the new high school design and over the past year, the AHS Building Committee has made substantial progress on identifying key sustainability features for inclusion. This supports the Town’s longstanding commitment to address environmental challenges and reduce energy use across all its facilities and operations. Aside from being the right thing to do, Arlington will receive approximately $3.5 million in additional reimbursement from the state by achieving a certain level of energy efficiency and sustainable design, as measured by the Leadership in Energy and Environmental Design (LEED) rating system from the U.S. Green Building Council.

Energy use considerations for the new AHS

The current high school is the Town’s largest energy user. To guide the AHS Building Committee’s energy-related work it is working towards three important outcomes:

1. Build a highly energy efficient building
2. Design for an all-electric building
3. Maximize onsite renewable energy production

Achieving these outcomes will lower long-term operating costs, create a more resilient building and provide a physical hedge against future energy price volatility, statutory requirements to phase out fossil fuel use, or policies that place an increasing price on carbon emissions.

Build a highly energy efficient building

A key metric for energy use is the Energy Use Intensity (EUI), measured in thousands of BTUs per square foot per year. It covers all site energy use (heating, cooling, lighting, plug loads, hot water, cooking, etc.). The current high school has an average EUI of about 66. Preliminary energy modeling of the new AHS shows an EUI of 33, with the potential to go below 30. Thus, the new building will use roughly half of the energy of the current building, yet will provide vastly superior comfort for occupants.

Design for an all-electric building

To achieve the town’s goal of being carbon neutral by 2050, it is essential to avoid direct use of fossil fuels in building. Although fossil fuels are used to generate electricity today, as the electricity grid gets cleaner over time, the carbon emissions and other pollution associated with the building’s electricity use will continue to decrease. Heating, ventilation and air conditioning (HVAC) solutions based on electric heat pump technology offer the most energy efficient options for heating and cooling. The current design includes the use of ground-source heat pumps as the primary HVAC technology.

Maximize onsite renewable energy production

Onsite renewable energy technologies such as rooftop solar power helps us achieve our climate and energy goals while reducing operating costs. There will be enough roof space on the new AHS to significantly expand the size of the existing solar array (which will be relocated to the part of the school built during the first phase of construction). The AHS Building Committee also anticipates installing a solar canopy over some of the onsite parking and is exploring other options for additional ground-mounted solar.

Accelerate Performance Program

Arlington is participating in the Accelerate Performance Program being offered through the Town’s two utilities, Eversource and National Grid. This pilot program offers enhanced incentives to adopt aggressive, but realistic, energy use targets early in the design process so that it is possible to achieve the desired energy performance at no or low incremental cost.

Participation provides the design team with free technical assistance paid for by the utilities and guarantees a minimum level of financial incentives of $0.50 per square foot, or just over $200,000. Actual incentive levels, which are likely to be higher, will be determined once the actual EUI of the new building is determined.

Additional sustainability features and goals

Beyond energy use, the current design includes other features that enhance the sustainability of the building, including:

• Use of light wells to bring daylight to interior spaces
• Use of environmentally-friendly finishes and materials
• Low-flow water fixtures
• Plans for full recovery of food waste from the cafeteria for composting or (potentially) conversion to energy
• Improved pedestrian and bicycle safety and circulation, including direct access to the Minuteman Bikeway
• Strong connections to the outdoors (physical, visual)
• Planning for an electric vehicle (EV) future, with 10% of parking spaces to be equipped with EV charging stations and the remainder being “EV ready”
• A target of a minimum of 75% diversion of construction and demolition debris from landfills (with a goal of 95%)

What’s next

During the next phase of the project, the design team will conduct more detailed energy modeling and a lifecycle analysis to determine the most cost effective and energy efficient solutions. As with any project of this complexity, trade-offs will need to be made, but the end result will be a building that is a model of energy efficiency and sustainability that we can all be proud of.

Resources:

• LEED Scoresheet (Schematic Design)
• Blog: Sustainability at the new AHS (June 2018)