Renovation Strategies for Office Building in Conformity with Energy Efficiency Standard: A Case Study of Pathumwan District Office Building, Bangkok

Abstract

The aim of this research is to explore renovative methods for office building envelope in Bangkok's Pathum Wan district, with the goal of reducing electricity consumption and minimizing heat transfer in compliance with energy efficiency standards. The total floor area of the office building is 3,400 square meters, comprising air-conditioned space (2,080 square meters, 61.2%) and non-air-conditioned space (1,320 square meters, 38.8%) on each floor. The study involves data collection on building materials, including solid walls, glass walls, and roof as well as the energy usage of electrical equipment in lighting systems, air conditioning systems, and electrical appliances within the office building. Subsequently, an analysis of energy usage data for the building, both before and after improvement, is conducted using Building Energy Code software version 1.0.6 (BEC v.1.0.6) for the purpose of identifying strategies for building materials modification, such as solid walls and glass walls, to reduce electricity usage and heat transfer costs, and calculating the appropriate payback period for these enhancements.

           The research findings reveal that the total heat transfer coefficient of the building before the improvements did not meet the specified standards. The Overall Thermal Transfer Value (OTTV) before the improvements was 62.578 Watts per square meter, exceeding the standard of 50 Watts per square meter. For the roof, the Roof Thermal Transfer Value (RTTV) before the improvements was 27.327 Watts per square meter, exceeding the standard of 10 Watts per square meter. Consequently, the research proposes three improvement strategies: 1) Enhancement of solid walls by adding insulation with a 9 cm air gap, reinforced with 25 mm Polyethylene Terephthalate (PET) panels and covered with 9 mm gypsum boards 2) Replacement of clear glass in transparent walls with green-tinted glass, reducing OTTV to 42.471 Watts per square meter 3) Improvement of the roof by using 75 mm thick glass wool insulation with a density of 12 kg/cubic meter, covered with an aluminum foil on the top layer, reducing RTTV to 6.956 Watts per square meter. Applying these modifications to solid walls, transparent walls, and the roof, the research demonstrates that the most cost-effective energy-saving strategy, with the shortest payback period, is a combination of these approaches. This results in a reduction of 15,058.38 kilowatt-hours per year, equivalent to 72,129.64 Baht per year. The total investment required for these improvements is 431,274.03 Baht, with a payback period of approximately 5.98 years.