DETERMINATION OF THERMAL COMFORT LEVEL IN PUBLIC OFFICE BUILDINGS: A CASE STUDY OF KWARA STATE OFFICE BUILDINGS

Abstract

The aim of the study is to evaluate effects of thermal comfort conditions in public office buildings in Kwara State, North Central, Nigeria. Seven public office buildings in Kwara State with regards to occupants’ evaluation of their indoor environmental conditions were measured and examined. The buildings comprised of two Mechanically Ventilated Buildings (Kwara State House of Assembly and Kwara State Advance Diagnostic center) and five other Naturally Ventilated office buildings which includes (Kwara State Government House, Kwara State Ministry of Finance, Federal Secretariat, Offa Local Government Area Secretariat and Patigi Local Government Secretariat). Ten offices were investigated in each building, measurements and readings of each parameter such as Floor Space (m2), Ambient Temperature (0C), Comfort Temperature (0C), Relative Humidity (%), Total Current (A), Lighting Levels (lux), Sound Levels (dB) and Number of Occupant(s) that are expected to be in each office were taken at intervals of 20minutes. The data were collated and computed to find average values of each parameter of each building. The buildings were of different sizes ranging from floor space of 57.5 m2 to 72.5 m2, different Ambient temperature ranges from 29.5°C to 30.4°C, different Relative Humidity ranges from 52% RH to 64% RH, Comfort Temperature 18.2°C to 21.4°C, Lighting Levels 347(lux) to 551(lux), Sound Levels 45(dB) to 55(dB) and Total Current of 60A to 158.6A. All these were done by taking physical and direct measurements with meter tape Thermometer, Hygrometer, Sound Meter Level, Photometer and Ammeter for total current required of each building. In most of the buildings, the type of air-conditioners found were windows, split or central air-conditioning systems. In some cases two or three types of the air conditioners were used. For this study, questionnaires was developed as a back-up to compare between the measurements and questions administered to 500 occupants and of which only 250 respondents responded of the seven buildings. The information sought for in the questionnaire were parameters directly related to the workplace. These parameters include air quality, temperature, air velocity, humidity, lighting, expected number of people in an office, colour of dress, material used in partitioning, number of furniture, number of electrical appliances among others. Micro Soft Excel was used to analyze the data collected and the results from these findings were compared with the 7 Point Sensational Scale of ASHRAE 55 and ISO 7730 standards. The outcomes showed that 85% of the respondents agreed that there was adaptive comfort level of 18.2˚C to 21.4˚C in both Naturally Ventilated office buildings and Mechanically Ventilated (Air-Conditioned) office buildings. Results also showed that, only three out of the seven office buildings met the standard 500 (lux) lighting criterion and sound levels measured in the buildings also showed that four of them were not comfortable in terms of acoustic minimum level of (55dB).