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Energy Consumption Evaluation and Optimization of Radiant and Personalized Cooling in Hot-Humid and Dry Climatic Zone
| Content Provider | Semantic Scholar |
|---|---|
| Author | Rajkumar, Surya |
| Copyright Year | 2020 |
| Abstract | Building sector continues to grow into one of the biggest consumers of energy in south Asian countries (classified majorly as very hot-humid and dry climatic zone). Estimates account space air-conditioning at nearly 50% of the energy consumption in commercial building sector, making energy a significant operational cost. Evolution of energy efficient space cooling system thus becomes a prerogative criteria (since the CDD10 is greater than 5000), paving the way for localized/personalized cooling. The research involves analysis of energy consumption patterns for a typical office space with a) Variable air volume system, b) Radiant floor cooling system c) Localized cooling by radiant panels on workstations. For the respective systems, zone cooling set point temperatures is varied based on climate responsive standard of India (representative of south Asian climate zone) and ASHRAE standard as baseline to arrive at the prospective cooling energy consumption patterns. Definitive deviance potential from the baseline present an opportunity to adopt energy efficient strategies. Greater impetus is provided to personalize cooling since from an energy consumption perspective, it reduces energy consumption by 30% over VAV system. Furthermore, tabs are kept on air distribution pattern and quality of air in the conditioned office space (by considering the standard k-Ɛ turbulence model) ensuring human comfort has greater degree of significance to energy consumption optimization. Introduction Globally, building construction and occupation have come under spotlight for its very strong linkages with energy use and climate impacts. Efficient use of energy is strongly emphasized over the last decade or so, since the reserve of our global energy resources is finite and depleting. The World Energy Outlook 2009, the global energy usage tracker of the Paris-based International Energy Agency says that the half of world’s population in cities is already consuming two-third of world’s energy. By 2030, cities will be consuming 73 per cent of world energy, accounting for 70 per cent of CO2 emissions. It projects big increase in energy and global CO2 from the increase in floor space in buildings of various types, especially in non-OECD countries (Organization of Economic Cooperation of Developed Countries) due to lifestyle changes. Within the climate and energy debate the urban consumption pattern in building units in cities thus becomes the focal point of mitigation. A study by IPCC 1996 indicates, share of energy consumption by residential, commercial and institutional building sector across the globe is expected at 38% by 2050. This increase is directly a result of rapid urbanization and growth of cities as major economic hubs in developing countries. Indian Green Building council says the global growth rate of construction Industry is 5.2% and specific to India, the figure nearly doubles to 10%. According to Energy Statistics 2013 of India’s National Statistical Organization (NSO) shows electricity accounted for more than 57 per cent of the total energy consumption during 2011-12 in India, and building sector is already consuming close to 40 per cent of the electricity. This is expected to increase to 76 per cent by 2040. With the rapid increase in urbanization and its associated energy usage, there exists a massive demand to provide energy optimization solution for building operation. Within a building, nearly 20% of the total energy demand is consumed as operational energy. Optimizing the operational energy demand in a positive way will influence the overall energy requirements of the building industry. Commercial offices offers a vivid opportunity to install/retrofit energy efficiency measures to optimize operational energy. Many research has benchmarked heating, ventilation and air-conditioning as the major energy guzzler in commercial office spaces with estimates at around 50 to 60% of overall energy consumed by building. Despite perceptions to the contrary, energyefficient offices are not expensive, difficult to manage or inflexible. Nor are they low on comfort and productivity. Energy-efficient techniques which work well tend to be reliable, straightforward, and compatible with management and user needs. Capital costs are often similar to those for normal offices, although budgets may be spent differently – for example, on measures to decrease cooling loads instead of on air-conditioning. Radiant cooling system and personalized radiant panel systems are few of such technology which is impending in India. Radiant cooling systems provide an opportunity to achieve significant energy and peak demand savings compared to conventional HVAC systems. Radiant cooling systems have circulation of water in pipes or tubes embedded in floor or ceiling or even on other surfaces such as walls. With radiant systems, people are cooled by radiant heat transfer from their bodies to adjacent ________________________________________________________________________________________________ ________________________________________________________________________________________________ Proceedings of the 16th IBPSA Conference Rome, Italy, Sept. 2-4, 2019 2011 https://doi.org/10.26868/25222708.2019.211011 Sensitivity: LNT Construction Internal Use surfaces—ceilings, walls, or floors—whose temperatures are held a few degrees cooler than ambient. This produces higher savings, since water has more than 3400 times the energy transport capacity of air. Since radiant cooling can take care of only sensible loads, parallel schemes are required for latent loads. These methods may form part of the ventilation strategy such as dedicated outdoor air systems. Even though the radiant cooling system is comfortable and energy saving, application of the same is limited by the condensation problem that might happen. Condensation occurs when the surface temperature of the panels is lower than the dew point temperature of room air. And the sudden increasing of moisture gain indoors or the decreasing of supply water to improve cooling capacity cause condensation (Wufen Jin et al.2015) This will directly affect the efficiency of the chiller and the operating conditions of cooling system. In order to avoid condensation, the surface temperature of panels should be controlled higher than the dew point temperature, which will limit the cooling capacity. Radiant systems are able to provide better and more uniform thermal environment [Olesen 2008], since the mean radiant temperature is also an important factor which affects the comfort of people. Various other benefits of radiant cooling system includes greater architecture flexibility, reduced operating and maintenance costs and more effective control of ventilation [Uponor]. The major function of an air conditioning system is to make people feel comfortable even during adverse outside conditions. In an office environment most of the time individual will be in his seat and working. By using radiant panels in the workstation, we tried to make the conditioning more localised so that the individual will feel more comfortable while working. So the amount of air to be treated will be drastically reduced which will directly affect the savings without any effect on the comfort of the people inside. The remaining area in the room was supplied with the fresh air by separate AHU’s specified as per the standards and hence the ventilation was also taken care of. In this research, we found out the energy saving comparison of a radiant ceiling cooling system and localized cooling with radiant panels on workstation with a conventional VAV system designed as per ASHRAE standard. This paper will definitely help as a basis for future researches in the radiant cooling areas for the designing of an energy efficient building. Methodology To provide thermally comfortable environment, conditioning the built space becomes a prerogative in hothumid and dry climatic zone. Upholding the thermal comfort index at acceptable levels offers a challenge to optimized building operational energy consumption. With this in hindsight, the study utilizes whole building energy simulation approach to analyze energy consumption patterns of three different zone airconditioning systems for a typical office space. The HVAC systems considered for comparison on the basis of comparable first costs are a) Variable air volume system, b) Radiant ceiling system and c) Personalized radiant panel system. The HVAC systems cater to the cooling demand of a 12 floor typical office layout with an overall built up area of about 7500 m. Figure 1 details the methodology adopted for study. ASHRAE 90.1-2010 is considered as basis for occupancy, envelope, lighting power density, equipment power density and associated operational schedules. The exact values are referenced in Table 1. Zone air set point temperature is also varied to determine the degree of energy optimization potential. Conventional model with a set point of 24 ̊C and set back of 26 ̊C and Indian Adaptive model with a climate responsive set point temperatures graphed in Figure 6 and a setback of +1.5 ̊C from set point are considered as the basis of HVAC system sizing. Figure 1: Study Methodology ________________________________________________________________________________________________ ________________________________________________________________________________________________ Proceedings of the 16th IBPSA Conference Rome, Italy, Sept. 2-4, 2019 2012 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.ibpsa.org/proceedings/BS2019/BS2019_211011.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
