High Performing Buildings - Winter 2011 - (Page 50)

CMTA outgrew its existing office space in 2008 and used the opportunity to design and build a new corporate headquarters. Plans called for the new facility to function as a laboratory to test new technologies and demonstrate their cost effectiveness to clients. goals Plans included additional meeting space in anticipation of hosting more client meetings to showcase the design and green features. All partners agreed the new building should: ensure green features complement the new sustainable development where the building is located; Consume minimal energy and be awarded an eNeRgY STAR rating of 100 (Models are important predictors, but benchmarking actual performance speaks loudest.); Be designed as a measurement and testing lab for green systems; earn LeeD gold certification without exceeding a 3% construction premium; and Take the first step toward becoming a net zero energy facility. The building exterior is designed to appear as three separate buildings, but is actually one. The first façade is a Victorian storefront and the other two are federal townhouses. The building walls are constructed of insulated concrete forms (iCF). iCF provides an excellent thermal barrier, reduces air infiltration and is a structural wall system. The added wall depth visually reinforces e n e r g y at a g L a n C e Annual energy use intensity (site) 15.7 kBtu/ft2 electricity 13.6 kBtu/ft2 renewable energy (Produced) 2.1 kBtu/ft2 Annual net energy use intensity 13.6 kBtu/ft2 Annual source energy 45.5 kBtu/ft2 Annual energy Cost index (eCi) $0.33/ft2 energY sTAr rating 100 BuiLding enveLOPe flat roof insulation 5 in. isocyanurate roof insulation on metal deck overall r-value r-32 Pitched Metal roof insulation blown cellulose at bottom of roof trusses overall r-value r-40 Walls Type insulated concrete forms: brick, 2 in. exterior styrofoam, 6 in. poured concrete, 2 in. interior styrofoam r-value 28 Windows u-value 0.37 solar Heat gain Coefficient (sHgC) 0.31 Visual Transmittance 72% Location latitude 38.24 n orientation east/West the look of a historic building. Roof insulation and high performance glass contribute to the thermal envelope that exceeds AShRAe/ ieSNA Standard 90.1-2004 by 20%. The building front faces west and includes large windows in the Victorian storefront for the first-floor conference rooms. Awnings that project 7 ft from the building provide solar and glare control. The second floor’s two separate work areas are daylit. Natural light is enhanced with six supplemental tubular devices that convey daylight from the flat roof to the second floor space. Where exterior offices are adjacent to the daylit work areas, both exterior and interior windows are provided to convey more natural light to the work areas. The daylit areas primarily have west and north exposures. These areas operate well in summer because the impact of the sun is later in the day. interior blinds reduce glare during winter when the angle of the sun is lower. Lighting The lighting system uses three strategies for reducing its electrical consumption: minimize lighting energy intensity; provide excellent lighting controls; and use daylight for the second floor work areas. The first strategy is largely responsible for the system’s low energy consumption. The lighting system is designed for 0.65 W/ft2, which exceeds the current energy code by 40%. The goal was to “right size” the lighting systems by designing them to meet AShRAe/ ieSNA 90.1-2007, but not over light. During design meetings staff indicated a preference for lighting thermal envelope Designing a high performance thermal envelope that met the neighborhood’s architectural guidelines was a challenge. The development guidelines required structures to be built to the property lines, which did not allow optimum orientation for daylighting. 50 HigH Performing Buildings Winter 2011

Table of Contents for the Digital Edition of High Performing Buildings - Winter 2011

High Performing Buildings - Winter 2011
Commentary
Contents
Portland State's Shattuck Hall
Oberlin College's Adam Joseph Lewis Center
Dell Children's Medical Center
CMTA Office Building
EPA Region 8 Headquarters
Honda's East Liberty, Marysville Auto Plants
Advertisers Index

High Performing Buildings - Winter 2011