Magazine serving the bus and rail transit & motorcoach operations since 1904
Issue link: https://metromag.epubxp.com/i/102390
green view when the sun is low on the horizon but still allows plenty of daylight to penetrate deep into the interior. North and south facing glazing utilizes insulated glass units, and the southfacing glass is shaded, which reduces cooling loads in the summer. All office and operator areas are heated and cooled using a ground source heat pump system. This overall system uses the earth to either preheat or pre-cool unconditioned air, which reduces the energy required by the actual HVAC units. TRANSPO's exterior wall assemblies include two inches of continuous rigid insulation, which negates thermal conductance through the building's metal studs. The cavities between the studs are filled with blown-in cellulose insulation that forms a tight and solid fill between each stud. This methodology, along with advanced detailing of the exterior envelope design, greatly increases the wall assembly's effective insulation value (R18 – R19) when compared to traditional methods of batt insulationfilled stud cavities — effective R- Value = 7.4, because of the thermal bridging. THE CASE FOR SUSTAINABILITY The structural concrete slab in the TRANSPO maintenance building is a large thermal mass that has the ability to store heat. A radiant heating system is installed in the concrete and two inches of rigid insulation is installed underneath the slab to ensure that the heat radiates into the interior space and not into the earth. The design of the system utilizes one gas boiler and one electric boiler. The gas boiler is used during the day and the electric boiler is used at night when the demand for electricity is much lower and thus much less expensive. Cutting edge sustainable design in fleet maintenance facilities is achievable with little additional cost to a project. Building codes and standards continually change and are forcing all projects to become more efficient with regard to their energy and water consumption. By looking at these baseline standards as opportunities, designers and owners can create incredible assets for transit agencies when they invest in their new maintenance and operations facilities. When designed correctly, substantial annual energy savings are achievable in new facilities. In addition, these new facilities provide healthier and happier work environments for employees. Increased efficiency and less lost time due to employees being out sick can also contribute to the overall bottom line. Sustainable design is no longer just a buzz word or fad. Sustainable transit facility design results in proven financial success and vitality for transit agencies. This vitality makes agencies more competitive in the 21st Century. Merlin Maley, AIA, LEED AP BDS&C;, is an associate and project manager at RNL. JANUARY 2013 mETRO mAGAZINE > 61