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Despite the huge technical and market potential for cost-effective energy efficiency investments in Southeast Asian markets, only a small fraction of this potential has been realised. Given that the major share of global future energy demand, and associated greenhouse gas emissions, will come from emerging economies, it is important to understand the barriers to mainstreaming energy efficiency into the financial sector. This paper focuses on public initiatives that support one of the main barriers: access to capital. The researchers chose Thailand as a case study because of the range of energy efficiency finance programmes that have been designed and implemented since the early 1990s. Interviews with 21 experts from government, the private sector and academia provided the core data for this research. The analysis employed a multi-level perspective and focused on the historical evolution of public support of energy efficiency finance in the country. We identified three distinct phases of public policy development over the past two decades. Despite an impressive variety of ambitious and creative programmes, the initiatives have not yet succeeded in integrating energy efficiency into the financial sector in a meaningful way. Some of the key lessons found are that (a) it is better to treat energy efficiency and renewable energy in separate financing initiatives, (b) governments find it challenging to design effective mechanisms to de-risk financial investments, and (c) international organisations play an important role in testing and facilitating the introduction of new financing approaches and mechanisms. In emerging economies, cost-effective implementation of energy efficiency measures is a promising alternative that can reduce the need for investment in large-scale power generation capacity. The researchers hope that this paper will contribute to more effective design of programmes to incentivise energy efficiency financing in Thailand and in other economies in Southeast Asia. [ABSTRACT FROM AUTHOR]

Abstract: In the tropics, daylighting from a side window requires shading to intercept direct sunlight from the window whilst allowing penetration of daylight from sky. In this paper, daylighting from a double-pane glazed window with enclosed horizontal slats (slat window) was investigated for which it is situated on either north or south wall of a room. Full-scale experiments and simulations were conducted to characterize distribution of the interior daylight from the slat window under a real tropical climate. Performance of the slat window was evaluated in terms of the “useful daylight illuminance” (UDI), interior daylight availability and light power density (LPD) of an integrated dimmable lighting system. Empirical formulas were developed for determining annual average LPD values of the dimmable lighting system over its served area. The LPD value can be used with a reduced form of the energy equation of Thailand's building energy code to evaluate the reduced annual electrical energy consumption for accreditation of the daylight use in a building. The analysis of life cycle cost proved that the daylighting from the slat window integrated with the dimmable lighting system is cost effective. [Copyright &y& Elsevier]

Abstract: Vernacular residential houses in Thailand were not heated nor cooled. The walls of such houses were constructed from wood and other light natural materials. Air-conditioning to cool interior spaces is now common and brick and concrete has replaced natural materials for walling. Even when a house is designed for air-conditioning, no insulation is used on the enclosing walls. It is generally believed that thick and heavy walls reduces cooling load in a space but insulation may not and is too costly. This paper presents results from an experimental and simulation study on comparative thermal performance of walls enclosing spaces that are used to serve three residential functions of bedroom, living room, and studio room. The study considers different levels of insulation and its placement at the interior and exterior surfaces on walls with and without windows, and for each functional use of a space. Use of external shading and blinds or curtain is not considered in this study. In all cases, the study concludes that insulation placed at interior wall surface improves wall thermal performance and is superior to that of exterior placement. The latter part appears to contrast with what have been found in similar studies taken under cool climate. [Copyright &y& Elsevier]

Abstract: This paper reports results of a study on characteristics of luminous efficacies of tropical global and diffuse horizontal solar irradiances using observed data from a daylight measurement station located in the southern area of Bangkok, Thailand (latitude 13.58°N and longitude 100.44°E). Mean hourly values of the efficacies and their frequency distributions are first presented. Through scatter plots, variations of the efficacies are then presented for different sky conditions covering from cloudy to clear skies. From our results, the pattern of variation of tropical global efficacy is noticed to be distinct from those in high latitude region. In this study, two all-weather models are developed empirically for predicting values of the tropical global and diffuse efficacies. The models are evaluated for their performances against some selected existing models. The results show that the proposed models predict well the tropical efficacies and outperform all other evaluated models. [Copyright &y& Elsevier]

This paper investigated the artificial neural network (ANN) modeling to forecast the one-hour ahead global and diffuse solar radiation using the observed data during 2019-2021 at a meteorological station in Bangkok, Thailand. Results from the statistical analysis portrayed the abundance of the tropical solar radiation and its large variation all year round. As a step to move advance the renewable energy use of the solar radiation at the location, the ANN forecasting models were proposed for all climatic conditions. The model input were the ambient temperature, solar elevation, and an insolation parameter namely normalized global solar radiation. The model performance was assessed by using the two statistic parameters: normalized mean bias error (nMBE), and normalized root mean square error (nRMSE). The results showed that the ANN models could forecast the global radiation with the nMBE of 1.79% and nRMSE of 26.20%. For the diffuse radiation forecast, the nMBE and nRMSE of the models were obtained at 7.78% and 36.21%, respectively. In order to demonstrate a benefit of the two developed ANN models, their forecasted horizontal data were employed to further predict the total solar radiation on vertical plane. Benchmarked with the smart persistence model, the developed ANN models possessed the higher forecasting accuracy for all weather conditions. [ABSTRACT FROM AUTHOR]

Abstract: Traditional houses and public buildings in Thailand were constructed from materials of low thermal mass and the walls were not insulated. Brick and concrete began to replace wood as walling material before air-conditioning was introduced into the country. New large buildings have glazed and closed windows so interior spaces require air-conditioning and forced ventilation. Up to the present, no insulation is used on walls. This paper presents results from an experimental and simulation study on comparative energy and economic performance of walls used to enclose air-conditioned spaces. The walls are externally and internally insulated to different thicknesses. The spaces are assumed to serve three commercial functions. Results show that insulation can generally help improve thermal performance of walls, but the function that a space serves dictates where insulation should be placed and how cost effective it is. [Copyright &y& Elsevier]

Abstract: This paper reports an experimental and simulation study on application of automated Venetian blind for daylighting in tropical climate. A horizontal blind system operating automatically under programmed control was constructed and integrated onto the glazed windows to form a window system with an automated blind in a room of a laboratory building. A dimming controller was also integrated to the lighting system of the room. Different operation schemes of the window system were devised and tested in the attempt to maximize energy savings while maintaining the quality of the visual environment in the room. Intensive measurement of illuminance of the interior space was undertaken during the experiments. A methodology for calculation of interior daylight illuminance and associated glare corresponding to the configurations of the experiments was adopted. The method was coded into a computer program. Results of calculation from the program agree well with those from experiments for all the schemes of operation conducted. The program was used to simulate the situation when each scheme of operation was implemented for a whole year. It was found that such window system with automated blind enabled energy savings of 80%, but a more sophisticated scheme also helped maintain the interior visual quality at high level. [Copyright &y& Elsevier]

Abstract: A solar-regenerated liquid desiccant ventilation pre-conditioning system has been installed and experiments were carried out for a period of nine months covering rainy, cold, and hot seasons in a hot and humid climate (Thailand). A heat exchanger was used to cool the dehumidified air instead of typical evaporative cooling to maintain the dryness of the air. The use of solar energy at the regeneration process and cooling water from a cooling tower makes the system more passive. The evaporation rate at the regeneration process was always greater than the moisture removal rate at the dehumidification process indicating that the concentration of the desiccant in the system would not decrease and so the performance would not drop during continuous operation. The system could reduce the temperature of the delivered air by about 1.2°C while the humidity ratio was reduced by 0.0042kgw/kgda equivalent to 11.1% relative humidity reduction. The experimental results were also compared with models in literature. [Copyright &y& Elsevier]

Abstract: In the tropics, the sky is luminous and variable. Distribution of luminance over the sky dome is non-uniform and varies widely and dynamically with weather condition. The high luminosity offers good potential for daylighting, but an understanding of the luminance distribution of tropical sky would help advance the movement for daylighting. This paper reports results of a characterization of sky luminance and radiance under the standard sky luminance patterns proposed by Kittler using measurements from a station located north of Bangkok. In accordance to the standard sky luminance classification, the sky patterns of north Bangkok mostly fall into clear and intermediate types. During cooler months, the sky is clear for over 60% of the time. In the midst of the rainy season, the sky falls into the intermediate category for over 40% of the time. The high incidence of clear sky on this classification differs from earlier results that use sky ratio and Perez''s clearness indices in the classification of sky condition. [Copyright &y& Elsevier]

Abstract: This paper reports an experimental and simulation study of application of radiant cooling using natural air for ventilation under hot and humid climate of Thailand. To avoid condensation of moisture on the cooling panel, the temperature of water supplied to the panel was limited to 24°C. This led to the expectation that the low heat reception capacity of the panel would limit its use only to situations when loads were low. Experiments were conducted in an experimental room over the hot and dry period of March, the humid period of May, and the cool period of December. The results generally confirm the good potential for application of radiant cooling. However, the room was served by radiant panels with a total area of 7.5m2. Its capacity was grossly inadequate during the hot period, even for night time application only. A special configuration was devised to achieve thermal comfort for the area served by the panel. The well-known TRNSYS program was used to simulate the use of cooling panels and conventional air-conditioning in the experimental room. Simulation results match experimental results very well. Using comfort criterion adopted by ASHRAE and International Standards Organization, results from experiments and simulation show that thermal comfort could be obtained with application of radiant cooling. [Copyright &y& Elsevier]

The use of OTTV as a measure of average heat gain across the building envelope of an air-conditioned commercial building has been accepted since it was introduced into Thailand and other ASEAN countries. Other studies have concluded that the average zone cooling coil load of an air-conditioning system can be taken to comprise the sum of the average external load, internal loads, and terms representing the storage effects of the exterior wall and internal masses of the building components in that zone. This conceptual relationship is used as the basis for postulating an equation that linearly relates the cooling coil load of a building zone over a period to its external factor represented by the OTTV and its internal factors represented by all internal loads over the same period. It is also used to postulate an equation that relates the energy use by the building to the cooling coil load and the direct loads. This study utilizes DOE-2 simulation program in a series of parametric runs to develop an OTTV formulation each for four types of commercial buildings. The resulting OTTV formulations were used in further parametric runs to develop a formulation each for the cooling coil load and for energy use in the form postulated. The formulations are validated using field audit results. [Copyright &y& Elsevier]

An investigation of atmospheric turbidity has been undertaken for tropical Thai sky. Values of turbidity indices, namely, Linke factor (TL), Angstrom coefficient (β) and illuminance turbidity factor (Til) are derived directly from measurements taken by pyrheliometer, Volz sunphotometer and beam illuminance meter. Monthly mean values and frequency of occurrence of the value of each turbidity index are used to characterize variations of atmospheric turbidity. Simple polynomial equations are developed for computing values of Linke factor and illuminance turbidity factor as functions of solar altitude angle. Using the values of Linke factor and illuminance turbidity factor obtained from the models developed, values of beam normal irradiance and illuminance can be calculated accurately under clear sky conditions. Values of daylight illuminance are useful for daylighting application that contributes to energy conservation for buildings. Knowledge of the size of beam normal irradiance is useful for calculation of cooling load in air-conditioning buildings in tropical climate. [Copyright &y& Elsevier]

This paper examines the requirements for designated buildings and the mechanisms for implementation of energy conservation programs in accordance with the Energy Conservation Promotion Act of Thailand. It then reviews the details of energy audits and implementation of energy conservation of designated commercial buildings and small government buildings. Through use of the DOE-2 simulation program and reference building models developed from energy audit information, it is shown that whole building retrofit is more cost effective than adopting individual options. It also points out that mobilizing involvement of the occupants of a building is a necessary and integral part of a successful energy conservation program. The paper also suggests means to overcome the present impediments to successful implementation of the programs. [Copyright &y& Elsevier]

Sky luminance and illuminance measurements from the daylight measurement station at the Asian Institute of Technology, Pathumthani, Thailand show that there is usable daylight throughout office hours on every day of the year. The variability of daylight, however, poses a challenge when attempting to characterize the sky and to develop models of daylight availability. Calculation of interior daylight and heat gain, and integration of electric lighting with daylighting are also a challenge. The disadvantages of glare and heat gain can overwhelm the benefits of daylighting in air-conditioned buildings if care is not taken. These problems are associated with clear and intermediate skies, and the combined frequency of occurrence of these conditions is 60%. [ABSTRACT FROM AUTHOR]

Presents a study on a model of light delivery and heat transfer based on the general configuration of a ceiling plenum. Details on the configuration done in multi-storey buildings; Methods for modeling light delivery and heat gain; Results and conclusion.

• Thermal performance of the radiant ceiling cooling was assessed for intermittent operation in tropical office environment. • Insulated envelope and outdoor air heat recovery improved both indoor comfort and energy saving of the radiant ceiling system. • The local people would achieve their neutral sensation by the radiant ceiling cooling for more than 95% of the office hours. • The radiant system saved the electrical energy up to 40% opposed to the conventional mixed-air system. This paper investigated the radiant ceiling cooling in office buildings in a tropical hot humid climate. Full-scale experiments were conducted in an outdoor laboratory chamber to observe the indoor thermal conditions and the envelope heat gain from the intermittent operation of the installed radiant chilled panels (RCP) coupled with an outdoor air unit (OAU). The radiant system was also modeled by using a simulation software namely Transient System Simulation Software (TRNSYS), and the calculation results from the model were compared to the experimental observations. In the simulation part, the validated TRNSYS model was adopted to assess the radiant system performance in a typical office environment under the four schemes of combinations of the technology options for the OAU and the building envelope. The perceived comfort from the radiant cooling was assessed based on the thermal sensation of the local subjects acclimatized to hot humid climate. The energy consumption of the radiant cooling was also apprised as opposed to the conventional mixed-air system. The simulation results presented an insight into the importance of the exhaust air heat recovery and the envelope insulation on energy saving and human comfort improvement for the radiant cooling. [ABSTRACT FROM AUTHOR]

In this study, a method is used to develop a model for estimating luminance distributions of Thai’s sky. From the sky characterization, five out of the fifteen CIE standard skies are selected for the distribution estimation. This selection represents the minimum sky types that best fit to the distribution records of Bangkok (Thailand) and cover three sky conditions of clear, partly cloudy, and overcast. The developed model uses the five standard skies each to estimate prevailing luminance distributions within a particular range of insolation condition defined by lower and upper limit values of Perez’s clearness ( ε ) and sky brightness ( Δ ). In this scheme, a stochastic search technique of evolutionary computation was applied to optimize limit values for an accurate sky classification. Equations of optimal limit values were also formulated as part of the method. From the comparative evaluation with other sky models (i.e. Perez’s model, ASRC-CIE model, Harrison’s model, CIE-Si model, and Igawa’s all-sky model), the proposed model offers an alternative option for generating luminance distribution of Thai’s sky. [ABSTRACT FROM AUTHOR]

Aqueous salt solutions (LiCl) were impregnated into a porous host matrix to create composite desiccant materials (silica gel). The authors of this paper fabricated and analyzed composite desiccant-coated aluminum sheets (DCAS) with varying LiCl mass concentrations. Nitrogen sorption results revealed that the Brunauer–Emmett–Teller (BET) surface area and pore volume of the composite desiccant-coated aluminum sheets decreased. Furthermore, composite DCAS had lower nitrogen sorption than silica-gel-coated aluminum sheets (SGCAS). According to the results, the composite DCAS had the highest thermal conductivity, measuring 6.1 Wm−1 K−1, doubling that of the SGCAS. For evaluating sorption kinetics, the linear driving force model (LDF) was used, and composite DCAS showed greater dynamic sorption quantities and sorption rate coefficients than SGCAS. Furthermore, three different moisture sorption isotherm models were used to fit the experimental results: the Brunauer–Emmett–Teller (BET) model, the Guggenheim–Anderson–Boer (GAB) model, and the double log polynomial (DLP) model. The DLP model was shown to be the best model for predicting the moisture sorption isotherms of DCAS. Additionally, the composite desiccant-coated heat sink (DCHS) of the thermoelectric dehumidifier (TED) was evaluated and compared to silica gel in terms of dehumidification capacity. According to the findings, the outlet air humidity ratio of the composite DCHS reached a minimum of 10.23 g kg−1, and the dehumidification capacity was 0.117 kg h−1 when the input electrical voltage was kept at 9 V. [ABSTRACT FROM AUTHOR]

Highlights: [•] The environmental impacts of a solar absorption chiller system (AC) are calculated. [•] The impacts are compared with an equivalently sized vapor compression system (VC). [•] The cooling production of the AC is simulated using system-specific parameters. [•] The VC system use-phase is the largest phase contributor to life cycle impacts. [•] The AC system yields lower impact potentials for all four impact categories. [ABSTRACT FROM AUTHOR]