Wajishani Gamage

Bio: Wajishani Gamage is an academic researcher from University of Moratuwa. The author has contributed to research in topics: Architecture & Daylighting. The author has an hindex of 2, co-authored 3 publications receiving 37 citations.

An Investigation of Thermal Comfort and Adaptive Behaviors in Naturally Ventilated Residential Buildings in Tropical Climates: A Pilot Study

Abstract: This article presents a pilot study of thermal comfort and adaptive behaviors of occupants who live in naturally ventilated dormitories at the campus of the National University of Singapore. A longitudinal survey and field measurement were conducted to measure thermal comfort, adaptive behaviors and indoor environment qualities. This study revealed that occupants living in naturally ventilated buildings in tropics were exposed to higher operative temperatures than what American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) comfort standards recommend for naturally conditioned spaces. However, they still felt that such conditions were acceptable. Two behavioral adjustments were found to have profound impacts on occupants’ acceptance of the imposed heat stresses: (1) increasing the indoor air velocity by turning on mechanical fans and opening the door/windows for cross ventilation, and (2) reducing clothing insulation by changing clothes and dressing in fewer clothes. Higher indoor air velocities were also associated with greater satisfaction with indoor air quality. The future study should develop a statistical model to correlate adaptive behaviors with temperature variations for tropical climates.

Effectiveness of air-well type courtyards on moderating thermal environments in tropical Chinese Shophouse

Abstract: In Southeast Asia with tropical climates, Chinese Shophouse (CSH) as a type of vernacular architecture is usually equipped with small intermediate air-well type courtyards, also known as ‘Tianjin’, to moderate the indoor thermal environment. This paper investigates the effectiveness of air-well type courtyards as passive design strategies on moderating indoor thermal environments in two CSHs located in Malacca, Malaysia. The study used a field survey and a CFD simulation. Statistical analyses of indoor air temperature and heat index (HI) measured at different locations of the CSHs show that intermediate spaces next to the air-wells had significantly lower air temperature and HI. Cross ventilation through the openings on the walls and air-wells resulted in a significantly lower normalized mean age of air and higher air velocity. The air-well is a suitable passive design strategy to reduce overheating during daytime and to increase cooling of building structure during night-time. The air-well courty...

mpact of vernacular architecture elements on patient waiting experience in rural government hospitals in Sri Lanka

Abstract: The role of architecture in hospitals is a sensitive topic; the prominence given to the programmatic requirements has led to disregard of the in-between function of waiting identified as the user experience in the recovery process. Healing, in other words cure means a state of physical & mental wellbeing that a patient experiences in a hospital. It’s a waiting process between the time of treatment & recovery. The waiting experience in Sri Lankan public hospitals is critical because spaces are designed only prioritizing standards while little consideration is given to the impact of local contextual parameters that generate familiar user experiences. This research investigates the impact of design options derived through principles abstracted by vernacular architecture elements on the waiting experience of patients in healthcare facilities. Vernacular elements of identification of centre and openness, articulation of transition space & domestic scaled spaces was used to interpret design options that can be adapted to reorganize the waiting scenarios of hallway, outpatient, and inpatient waiting spaces. The research further investigate how they will help alleviate the user experience of waiting and increase wellbeing.

An analysis of daylighting performance of learning spaces in local government sector schools in Kandy

Abstract: Natural lighting creates a pleasant environment, promotes healthier conditions and saves energy, and is an important factor in the design of education institutions. Many research indicates the positive impacts of better daylighting integration in educational spaces for student’s health and wellbeing. For this research, an in-depth lighting integration analysis was carried out in three typical classrooms in Berrewaerts college Kandy, Sri Lanka. A field study comprised of a questionnaire-based survey and measurement of illuminance was combined with daylight simulation using Autodesk Ecotect 2011 & Autodesk Revit. The study reveals that lack of awareness in integration of natural light with the design can either result in increasing the negative effects of excessive daylight exposure or lack of adequate daylighting. In upper levels and east facing classrooms the main problems were associated with high levels of daylight such as excessive shadow and light patches, uneven light distribution and color distribution and impede perception of objects and text. At ground floor level and south facing classrooms, when natural light is not properly integrated with the design resulted in uneven light distribution, non-uniformity of light resulted in difficulty in reading at work plane and impede the visual perception of objects and text.

A review of net zero energy buildings in hot and humid climates: Experience learned from 34 case study buildings

Abstract: Sustainable development in the building sector requires the integration of energy efficiency and renewable energy utilization in buildings. In recent years, the concept of net zero energy buildings (NZEBs) has become a potential plausible solution to improve efficiency and reduce energy consumption in buildings. To achieve an NZEB goal, building systems and design strategies must be integrated and optimized based on local climatic conditions. This paper provides a comprehensive review of NZEBs and their current development in hot and humid regions. Through investigating 34 NZEB cases around the world, this study summarized NZEB key design strategies, technology choices and energy performance. The study found that passive design and technologies such as daylighting and natural ventilation are often adopted for NZEBs in hot and humid climates, together with other energy efficient and renewable energy technologies. Most NZEB cases demonstrated site annual energy consumption intensity less than 100 kW-hours (kWh) per square meter of floor space, and some buildings even achieved “net-positive energy” (that is, they generate more energy locally than they consume). However, the analysis also shows that not all NZEBs are energy efficient buildings, and buildings with ample renewable energy adoption can still achieve NZEB status even with high energy use intensity. This paper provides in-depth case-study-driven analysis to evaluate NZEB energy performance and summarize best practices for high performance NZEBs. This review provides critical technical information as well as policy recommendations for net zero energy building development in hot and humid climates.

Occupant behaviour and control of indoor environment in Danish dwellings

Abstract: Abstract Repeated surveys of occupant control of the indoor environment were carried out in Danish dwellings from September to October 2006 and again from February to March 2007. The summer survey comprised 933 respondents and the winter survey 636 respondents. The surveys were carried out by sending out invitations to addresses obtained from a Danish register along with information on dwelling characteristics. Meteorological data was obtained from the Danish Meteorological Institute. Four control mechanisms (window open/closed, heating on/off, lighting on/off and solar shading in/not in use) were analysed separately by means of multiple logistic regression in order to quantify factors influencing occupants’ behaviour. The window opening behaviour was strongly related to the outdoor temperature. The perception of the environment and factors concerning the dwelling also impacted the window opening behaviour. The proportion of dwellings with the heating turned on was strongly related to the outdoor temperature and the presence of a wood burning stove. The solar radiation, dwelling ownership conditions and the perception of the indoor environment also affected the use of heating. The results of the statistical analyses form a basis for a definition of standard behaviour patterns which can be used to make calculation of energy consumption of buildings more accurate.