Efficiency and Sustainability


Salt Pine Social is one of Maine's most energy-efficient and sustainable restaurants. Customers enjoy their dining experience with minimal environmental impact, thanks to a sophisticated energy design. The building's ventilation, heating, cooling, refrigeration and lighting all smartly work together to ensure the space is wonderfully comfortable while using much less energy than a conventional restaurant.

The location in downtown Bath gives the project an enormous sustainability head start: reusing the bones of an existing building saves resources, leverages existing infrastructure, and maintains the economic vitality of the core of the City of Ships. Tightly insulating the shell of the building reduces the heating and cooling load dramatically, while also eliminating drafts and preventing humidity problems. Heating and cooling with super-efficient electric heat pumps further reduces energy use, and prevents pollution, as the electricity in Maine is supplied more and more by clean and renewable sources such as solar, wind and hydropower.

An energy recovery ventilation system provides just the right amount of fresh air for the number of customers in the restaurant. The system is constantly exchanging air, exhausting stale air while transferring the energy in it to fresh incoming air. The combination of a tightly insulated building and an energy recovery ventilator means less heat lost in the winter and less cooling lost in the summer. This ventilation strategy maintains excellent indoor air quality while dramatically lowering heating and cooling bills.

The airflow throughout the whole restaurant is carefully balanced so that air flows into the kitchen and bathrooms, and then out of the building. Maintaining a constant slight negative air pressure toward these areas ensures that customers breathe clean, fresh air without feeling drafts.

In the kitchen, an equally advanced ventilation strategy is employed. A smart kitchen hood exhaust system constantly monitors the cooking surfaces, ramping up and down the hood exhaust rate as needed. When cooking surfaces are not in full use, the hood automatically reduces the amount of air it removes from the kitchen, which saves energy in several ways. Slower fan speeds directly save electricity. Less air being removed from the kitchen means less outdoor air needs to be added to the kitchen through the "make up" air unit. But more importantly, in the winter, less cold air flowing through the restaurant and out the kitchen hood means lower heating bills. On sweltering summer days, less kitchen exhaust lowers air conditioning loads, as less humid hot air from outside is brought inside.

Air conditioning expenses are further lowered by an innovative split-system heat pump water heater. Waste heat in the kitchen, particularly from the dishwasher, is used to make hot water. Unlike a conventional commercial kitchen design, which vents the dishwasher to dump heat outdoors, at Salt Pine Social, a heat pump collects waste heat from above the dishwasher and stores it in a water tank. In other words, air conditioning the kitchen makes hot water; waste heat from every load of dishes helps heat the water for the next load.

Another system which collects waste heat and makes beneficial use of it is the walk-in cooler. A cooler in a restaurant must constantly move heat from inside it to somewhere else. Taking steps to reduce the heat flowing into the cooler makes it possible to consider a wider range of strategies for handling this waste heat. At Salt Pine Social, a super-efficient heat pump system moves heat from the cooler to the unheated basement. This slightly warms and dries the basement. The basement works as a heat dump zone because the energy flow between cooler and basement is minimal: the cooler is on the north side of the building, so it is always in shade, and insulated with spray foam.

But perhaps the most dramatic energy savings on display at the new restaurant are the lights. LEDs are five times more efficient than old-fashioned incandescent light bulbs, and are even significantly more efficient than obsolescent "energy-saving" fluorescent lights. LED lights turn on instantly, are dimmable, provide excellent color rendering, are shatterproof, and contain no mercury or other toxic materials. Because they run cooler and can be packaged in smaller fixtures than older lighting technology, LEDs are safer, don't require gaps in ceiling insulation, and help reduce air conditioning loads. High-quality, long-lasting, and high-performance LED lights round out the smart energy design at Salt Pine Social.

All of the mechanical systems working together will eliminate the use of fossil fuel on site for everything except cooking on a gas range. The overall energy intensity of the restaurant will be less than half of a conventional restaurant. These huge gains in efficiency won't come at the expense of comfort or safety; on the contrary, customers and staff will enjoy a better experience at Salt Pine Social thanks to its commitment to sustainability.

For more information about the design and implementation of the high-performance energy-saving systems at Salt Pine Social, contact Fred Horch of Spark Applied Efficiency, (207) 200-4685 or fred@sparkae.com.