More Kudos for Charlestown Wine & Spirits

Intoxicating Energy Savings at Local Package Store

By DAVE FISHER/ecoRI News staff

CHARLESTOWN — The building at 4625 Old Post Road is an green dream come true. The building was designed from the ground up with an eye toward extreme efficiency. Geothermal heating and cooling, computer-controlled lighting, reused and recycled materials used in its construction. The building’s “green cred” is enough to make you want to visit, but most visitors have another thing on their mind: adult beverages.

Charlestown Wine and Spirits opened its new location to a flurry of media attention earlier this year. While this may be old news to some of you, we at ecoRI News understand that the opening of the uber-green business, while newsworthy, isn’t the real story. Now that the store has been operating for a few months, the real news — how much of the business’s energy and operating costs have been offset by the efficiency of the structure? — comes to light.

Oyster Works' Andrew Baer shows off a cutaway of the custom fabricated wall panels used to build Charlestown Wine and Spirits. (Dave Fisher/ecoRI News staff)The building itself is quite a marvel. Designed by Charlestown’s own Oyster Works design and architecture firm, and employing its "Sensibly Green" design principles, the building began with the fabrication of wall and ceiling panels that have a ridiculous R30 and R40 insulation ratings, respectively. A series of three closed-loop geothermal heat pumps — embedded 450 feet underground — provide all of the heating and most of the cooling needs of the store, and that includes one of the two beer coolers. The geothermal system was designed to capture the specific amount of BTUs needed to heat and cool the store. 

The second beer cooler — chilled by conventional electric compressors — is activated only during the tourist season, allowing a complete shutdown during non-peak seasons. All of the excess heat from cooling the building and the beer coolers is returned to the bedrock via the geothermal system, increasing the ambient heat in the bedrock and effectively storing the BTUs for winter heating purposes. The store uses no oil, propane or natural gas for heating purposes.

Andrew Baer, project manager for Oyster Works, explained the system in terms of the building's envelope. “Every building has an envelope,” he said. "The envelope dictates the amount of BTUs used. If the building’s envelope isn’t tight, you will have loss of heat energy.”

The store’s envelope is comprised of four “micro-climates” and heat is delivered or removed from each of the sections as needed by a system designed around each climate, rather than by the traditional "one-space, one-thermostat" approach.

To achieve that tight envelope, the individual panels used to construct the building were fabricated to specification offsite, then connected and sealed onsite. The panels have no timbers running from the sheath of the building to the interior, reducing thermal bridging and increasing the overall R-value of the solid Styrofoam panels. This offsite, custom fabrication also reduced the amount of onsite waste created during construction.

The store’s heat is delivered through radiant floor heating, which heats only the first 7-10 feet of the space, rather than the entire two stories of the open timber structure. The building's cooling system begins with a dehumidifier — an essential component to deal with New England’s super-humid days of summer — and finishes with air circulated over water-cooled coils. The cooling system, which like most heat-pump applications, is just the heating system running in reverse, pulling heat from the air and depositing it into the groundwater and bedrock surrounding the site.

So what does this all mean vis-à-vis energy usage and savings to the business owners? Well, to qualify for a U.S. Government Energy Star rating the average annual electrical usage for a grocery and convenience store must 52.5 kilowatt-hours per square foot or lower. Based on National Grid bills for the past four months, the store’s electrical usage is 19.9 kilowatt-hours of electricity per square foot. This represents 62 percent less energy than the U.S. Energy Star benchmark for comparable stores.

The energy savings are the result of Oyster Works’ detailed analysis, design, energy-efficient building systems and its critical attention to detail, but the “green-ness” of the building doesn’t stop at the heating/cooling system.

The building’s lighting is computer controlled and task and use specific. That is, each light switch has multiple settings that range from “open for business” to “special events” to “receiving.” Two-thirds of the parking lot is covered with permeable pavers that allow stormwater to enter the soil almost immediately rather than being accelerated by impermeable surfaces such as concrete and asphalt. The lot also gently slopes toward the back of the property into a retention pond that mitigates the infiltration of stormwater from heavy rain events. The building's siding is made from recycled PVC, and the fieldstone wall in front is comprised of stones from dismantled walls on other sites. On top of all of this, all of the labor and contractors used in the onsite construction of the building were from the Ocean State.

“The concept of value in a building is changing," Baer said. "Sensibly green design equals efficiency plus affordability. That must include the construction, operating and life-cycle costs of the entire structure. Real efficiency is achieved through reducing demand through conscious design.”