Abstract:
A decision to retrofit the United Nations Environment Program office to reduce greenhouse gas emission by 50% was recently announced. In its existing condition, electricity consumption was measured at 618 kWh/m[superscript 2].yr, of which 60 % (371 kWh/m2.yr) was consumed by cooling energy. The research studied energy and cost efficiency by analyzing four significant variables on cooling load: building form, building materials, installed equipment and the microclimate. The study was divided into two phases: Phase 1 was concerned with renovation of opaque envelopes by installing 4" of fire-spread protection foam insulation (EIFS) on external walls (13% of total envelop), with a total U-value of 0.05 Btu/hr.ft[superscript 2]. [superscript o]F. The refit also involved installing 9 thick fiberglass insulation on ceilings (43% of total envelop) with a total U-value of 0.03 Btu/hr.ft[superscript 2]. [superscript o]F, and 1½" thick PU foam on concrete floors (41% of total envelop) with total U-value of 0.12 Btu/hr.ft[superscript 2]. [superscript o]F. Phase 2 involved installing triple heatstop glass (3% of total envelop) with a total U-value of 0.19 Btu/hr.ft[superscript 2]. [superscript o]F and a COP 3.45 air conditioning system. Microclimate was determined by constant variables. The research found that Phase 1 of the renovation reduced the cooling load energy by 142 whr/m2.yr and CO[subscript 2] emissions by 78 kgCO[subscript 2] /m[subscript 2] .yr (13%), at an investment cost of 3,871 baht/m2 and giving a 7-year period of return. Phase 2 reduced cooling load energy by 475 whr/m[subscript 2] .yr and CO[subscript 2] emissions by 261 kgCO[subscript 2] /yr (87%), requiring an investment of 5,395 baht/m2 with a 3-year period of return. Due to the reduction of Mean Radiant Temperature (MRT) and infiltration, occupants are perceptibly more comfortable in air-conditioned areas referring to bioclimatic standard and CO[subscript 2] standard level.