Implementing Solar HVAC Systems in Schools

Implementing Solar HVAC Systems in Schools

Next >

Ali Baniyounes

Applied Science Private University Amman, Jordan

AbstractSchools are unlike any other commercial property since they have special energy needs. High heat and electricity loads are the main key elements faced by design engineers. By implementing renewable energy for heating, ventilating and air conditioning (HVAC) in schools, a significant amount of energy savings can be achieved and this will also contribute in reducing gas emission. All power plants generating electricity today produce gases and waste that have a negative impact on the environment. During the summer the demand for electricity increases dramatically because of the extensive use of HVAC systems, this increases the peak electric load, causing major problems in the national electric supply system. Acknowledging that global warming is the number one environmental threat, because of gas emission, puts a serious pressure on mankind to reduce carbon dioxide (CO2) emission to the atmosphere. High fuel prices force decision makers to adopt and encourage renewable energy resources. Implementing renewable energy might be a way to reduce the demand for electricity. In addition, most renewable energy systems are being developed in ways that reduce the need for convention fuel. This study presents a thorough review on zero emissions technologies for the built environment. The specific attention is given for subtropical climate in Australia. Both technical and economic feasibility compared to only grid connected HVAC are also discussed. This study contributes to the understanding and process development for implementing solar assisted HVAC systems in buildings in Jordanian climates

Keywords:- Component; Renewable Energy; HVAC; Entertainment Centres; Zero Emissions.

I. INTRODUCTION

Energy needs of a schools can not be compared with typical consumption of any other building (commercial or residential) because the energy needs is largely dependent on the specific event activity. Normally in schools the peak of required energy occurs after normal working hours or when offices are closed. Energy consumption usually depends on the time table of the center and event public attendance. Entertainment center air conditioning is one of the major consumers of electrical energy due to the high number of people attending a performance and the instruments used during the event.

Associated with air conditionings high use of energy is significant environmental pollution, in the form of greenhouse gas emissions with the resultant climate change impacting not only upon our environment, but also our health and productivity [1]. Of the many ways of individually addressing air conditionings impact upon the grid and environment, solar air conditioning is one of the few solutions that provides cooling and addresses the demand of peak loading, and does so with reduced environmental impact. Solar air conditioning is a way to reduce the demand for electricity which means less demand

for fuel and coal. In addition, many solar air conditioning systems are constructed in ways that eliminate the need for chloroflurocarbons CFC, Hydrochlorofluorocarbons HCFC or Chlorofluorocarbons HFC refrigerants. Alternatives to use solar energy is waste heat from different industrial processes such as refineries, garbage treatment facilities etc. [2]. Energy costs, for example, which typically represent up to 10 percent of a centers operating budget, can be reduced easily by 30% to 35% according to Fried Gil from sport facility management second edition [2-3]. Almost all schools treat energy costs as ongoing, uncontrollable costs extracted from core funding. By reducing energy costs, schools can keep more money for core funding and increase their discretionary spending [4]. This study presents why and how solar cooling technologies contribute to achieve energy and monetary savings and to reduce green house gas emissions.

II. WHY SOLAR COOLING?

During the summer the demand for electricity increases because of the extensive use of HVAC systems, which increase the peak electric load, causing major problems in the electric supply. The energy shortage is worse during dry years because of the inability of the hydroelectric power stations to function and cover part of the peak load. The use of solar energy to drive cooling cycles for space conditioning of most buildings is an attractive concept, since the cooling load coincides generally with solar energy availability and therefore cooling requirements of a building are roughly in phase with the solar incidence. Solar cooling systems have the advantage of using absolutely harmless working fluids such as water, or solutions of certain salts. They are energy efficient and environmentally safe. They can be used, either as stand-alone systems or with conventional air conditioning, to improve the indoor air quality of all types of buildings. The main goal is to utilize "zero emission" technologies to reduce energy consumption and CO2 emissions [5]. The schematic diagram of a solar air conditioning system is shown in Fig. 1.

. Figure 1 Standard system schematic [5].

III. TECHNOLOGIES APPLICABLE FOR SOLAR THERMALLY DRIVEN COOLING

Cooling can be obtained from many different ways. The majority of them have a direct or indirect origin with the sun, such as fossil fuels. The expression solar cooling is usually restricted to when the solar radiation is the direct agent of cooling. In order to evaluate the potential of the different solar cooling systems, a classification has been made by [6] names air conditioning systems, solar heat is required to drive the cooling process. Thus, solar assisted air conditioning systems operated so far may be classified into two types: closed systems and open system, where closed system these are thermally driven chillers which provide chilled water, that is either used in air handling units to supply conditioned air (cooled, dehumidified) or that is distributed via a chilled water network to the designated rooms to operate decentralized room installations, e.g. fan coils. Market available machines for this purpose are absorption chillers (most common) and adsorption chillers (a few hundred machines worldwide, but of rising interest in solar assisted air conditioning). Open systems; allows complete air conditioning by supplying cooled and dehumidified air according to the comfort conditions. The refrigerant is always water, since it is in direct contact with the atmosphere. Most common systems are desiccant cooling systems that use a rotating dehumidification wheel with solid sorbent as reported in J Peeples [7]. According to M Delorme [8], it has been possible to calculate the COP of the chiller based on the available temperature and flow measurements according the following formulas:

Qc QcQcCOPq

Next >