scholarly journals Simulation of Thermal Performance and Cost Benefits of Cool Roof Options through Building Engineering System Software

2020 ◽  
Vol 39 (4) ◽  
pp. 806-814
Author(s):  
Aftab Ahmed Sahito ◽  
Rizwan Ahmed Memon ◽  
Khanji Harijan ◽  
Pervez Hameed Shaikh
Keyword(s):  
Air Temperature ◽  
Thermal Performance ◽  
Temperature Difference ◽  
Energy Savings ◽  
Payback Period ◽  
Engineering System ◽  
Cool Roof ◽  
Cost Benefits ◽  
Save Energy ◽  
Building Engineering

The cool roofs in buildings is a promising option to deal with summer Urban Heat Island (UHI) effects. In context to that, studies on different cool roof materials are widely available; however, there is a dearth of studies on insulating material benefits and implication for tropical and sub-tropical climate zones. This work investigates thermal performance, energy savings and cost benefits of cool roof materials. For this study, simulation of various cool roof materials such as Marble, Expanded Polyurethane Spray (EPS), Poly Vinyl Chloride (PVC), Spray Polyurethane Foam (SPF) , Extruded Polystyrene Foam (XPS), Thermocol sheet, Asphalt tile, Gypsum tile and Jumbolon-board have been carried out using Energy Plus software package. The results of zone air temperature show that maximum zone air temperature occurs in the month of May. The maximum zone air temperature obtained for conventional roof is 32.1oC, whereas that for Thermocol sheet, SPF, XPS, Jumbolon-board, EPS, marble, PVC, Asphalt tile and Gypsum tile is 28.8, 28.9, 28.8, 29, 29.1, 31.9, 30.5, 30.2 and 30.7oC respectively. Conventional roof surface outside and inside temperature difference is 2.90C, whereas, roof surface outside and inside temperature difference for Thermocol sheet, XPS, Jumbolon-board, SPF, EPS, marble, PVC, asphalt tile and gypsum tile is 9.2, 9.3, 8.7, 7.5, 8.1, 3, 3.1, 3.3 and 2.20C, respectively. Notably, XPS, Thermocol sheet, SPF, Jumbolon-board, EPS, Marble, PVC, Asphalt tile and Gypsum tile cool roof materials can save around 5.47, 5.38, 5.35, 5.15, 4.93, 1.09, 2.62, 2.31 and 2.18 MWh annually, respectively for the selected building. The payback period for marble, PVC, gypsum tile and asphalt tile is above 1 year, whereas the effective payback period obtained for XPS, Thermocol sheet, SPF, EPS and Jumbolon-board varies from 3 to 6 months. It is concluded that the cool roof materials may be used effectively to save energy and cost.

A Numerical Model for Thermal Performance of an Unglazed Transpired Solar Collector

2011 ◽  
Author(s):  
Saeed Moaveni ◽  
Patrick A. Tebbe ◽  
Louis Schwartzkopf ◽  
Joseph Dobmeier ◽  
Joseph Gehrke ◽  
...  
Keyword(s):  
Numerical Model ◽  
Air Temperature ◽  
Thermal Performance ◽  
Solar Collector ◽  
Energy Savings ◽  
Ambient Air ◽  
Solar Collectors ◽  
Heating Unit ◽  
Plate Temperature ◽  
Building Wall

In this paper, we will present a numerical model for estimating the thermal performance of unglazed transpired solar collectors located on the Breck School campus in Minneapolis, Minnesota. The solar collectors are installed adjacent to the southeast facing wall of a field house. The collectors preheat the intake air before entering the primary heating unit. The solar collector consists of 8 separate panels (absorber plates). Four fans are connected to the plenum that is created by the absorber plates and the adjoining field house wall. All fresh air for the field house is provided by the solar collectors before being filtered and heated by four, independent two stage natural gas fired heaters. Moreover, the following data were collected onsite using a data acquisition system: indoor field house space temperature, ambient air temperature, wind speed, wind direction, the plenum exit air temperature, the absorber plate temperature, and the air temperatures inside the plenum. The energy balance equations for the collector, the adjacent building wall, and the plenum are formulated. The numerical model is used to predict the air temperature rise inside the plenum, recaptured heat loss from the adjoining building wall, energy savings, and the efficiency of the collectors. The results of the numerical model are then compared to the results obtained from the onsite measurements; which are in good agreement. The model presented in this paper is simple yet accurate enough for architects and engineers to use it with ease to predict the thermal performance of a collector.

scholarly journals A Cost Benefit Analysis of Secondary Glazing as a Retrofit Alternative for New Zealand Homes

2021 ◽  
Author(s):  
◽  
Nick Smith
Keyword(s):  
New Zealand ◽  
Thermal Performance ◽  
Energy Savings ◽  
Cost Benefit Analysis ◽  
Housing Stock ◽  
Cost Benefit ◽  
Cost Effective ◽  
Cost Benefits ◽  
Acrylic Sheet ◽  
Thin Plastic

<p>Homes with single glazing represent a large majority of the New Zealand housing stock. With the recent changes to the NZ Building Code Clause H1 Energy Efficiency, new homes require higher glazing thermal performance. This will lead to an increased need for cost effective methods to improve window thermal performance in existing single glazed homes without completely replacing the windows, which includes 'secondary' glazing. There are several secondary glazing options available including 'stick-on' plastic glazing as well as aluminium framed glass solutions that are installed inside the existing joinery. Secondary glazing is marketed as a cost effective alternative to insulated glazing units, providing both improved acoustic and thermal insulation to existing windows. There is little information regarding the in-use performance and cost benefits of secondary glazing in New Zealand. This thesis explores the efficacy of the secondary glazing products when installed in existing single pane frames. A guarded hotbox was used to make thermal resistance measurements on a typical single glazed aluminium window with timber reveal liner. Four common secondary glazing systems were retrofitted into the window - (1) thin plastic film; (2) magnetically-attached acrylic sheet; (3) aluminium framed secondary glazing; and (4) aluminium framed low emissivity (low-E) secondary glazing. Models of 'typical' New Zealand homes created in the ALF building thermal simulation programme were used to explore the heating energy savings and cost benefits provided by the different secondary glazing systems in a range of locations. Of the tested products, the low-E secondary glazing produces the largest cost-benefits. At current energy and material costs, secondary glazing was found to not be a financially viable solution in warmer climates such as Auckland. In cooler climates such as Christchurch and Dunedin, secondary glazing was found to be a cost effective retrofit alternative for existing single glazed homes</p>

Impact of Optimal Discharge Air Temperature and Minimum Airflow

2009 ◽  
Author(s):  
Young-Hum Cho ◽  
Young-hoon Jung ◽  
Mingsheng Liu
Keyword(s):  
Air Temperature ◽  
Thermal Stratification ◽  
Room Temperature ◽  
Energy Savings ◽  
The Other ◽  
Waste Energy ◽  
Heating Load ◽  
Save Energy ◽  
Air Circulation ◽  
The Impact

Airflow and discharge air temperature can be varied to maintain room temperature setpoint according to heating load. Increasing discharge air temperature and the decreasing airflow can save energy, but it causes reduced air circulation as supply air temperature rises above the space temperature. On the other hand, increasing airflow can improve air circulation; however, it may waste energy. The objective of this study is to identify the correlation between the minimum airflow and discharge air temperature that will maintain room thermal comfort. Optimal room airflow and discharge air temperature were analyzed, and the impact of room airflow and discharge air temperature on thermal stratification was evaluated and potential energy savings was estimated. Its performance was conducted through field experiment.

Energy Saving and Payback Period for Retrofitting Air Conditioning Systems in Taiwan

2011 ◽  
Vol 121-126 ◽  
pp. 2850-2854 ◽  
Author(s):  
Chung Yi Chang ◽  
Hsien Te Lin ◽  
Chun Ta Tzeng ◽  
Kuan Hsiung Yang ◽  
Yew Khoy Chuah ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Frequency Conversion ◽  
Energy Savings ◽  
Thermal Environment ◽  
Co2 Concentration ◽  
Payback Period ◽  
Water Volume ◽  
Building Energy Management ◽  
Ac Systems ◽  
Save Energy

In Taiwan, AC systems in buildings with central air conditioning account for over 45% of the total electricity consumed. Inefficient and poorly designed AC systems in existing buildings waste considerable amounts of money and energy. Therefore, retrofitting AC systems has become a widely adopted strategy to save energy while maintaining a comfortable indoor thermal environment. This study analyzes the potential energy savings and payback period of retrofitting AC systems in public buildings. In addition to the required Building Energy Management System (BEMS), several measures are introduced to reduce energy consumption during retrofitting. The main measures include testing, adjusting, and balancing (TAB) of existing AC systems; replacing over-designed chillers with chillers with smaller capacity; installing frequency conversion in original systems, such that they become variable water volume (VWV) and variable air volume (VAV) systems; and utilizing CO2 concentration control and pre-cooling air systems. Based on analytical results, we conclude that AC system retrofitting can reduce total energy usage by 11.75%, while the average payback period for a retrofit project is 4.71 years, demonstrating that AC system retrofitting in Taiwan is economically sound.

scholarly journals A Cost Benefit Analysis of Secondary Glazing as a Retrofit Alternative for New Zealand Homes

2021 ◽  
Author(s):  
◽  
Nick Smith
Keyword(s):  
New Zealand ◽  
Thermal Performance ◽  
Energy Savings ◽  
Cost Benefit Analysis ◽  
Housing Stock ◽  
Cost Benefit ◽  
Cost Effective ◽  
Cost Benefits ◽  
Acrylic Sheet ◽  
Thin Plastic

<p>Homes with single glazing represent a large majority of the New Zealand housing stock. With the recent changes to the NZ Building Code Clause H1 Energy Efficiency, new homes require higher glazing thermal performance. This will lead to an increased need for cost effective methods to improve window thermal performance in existing single glazed homes without completely replacing the windows, which includes 'secondary' glazing. There are several secondary glazing options available including 'stick-on' plastic glazing as well as aluminium framed glass solutions that are installed inside the existing joinery. Secondary glazing is marketed as a cost effective alternative to insulated glazing units, providing both improved acoustic and thermal insulation to existing windows. There is little information regarding the in-use performance and cost benefits of secondary glazing in New Zealand. This thesis explores the efficacy of the secondary glazing products when installed in existing single pane frames. A guarded hotbox was used to make thermal resistance measurements on a typical single glazed aluminium window with timber reveal liner. Four common secondary glazing systems were retrofitted into the window - (1) thin plastic film; (2) magnetically-attached acrylic sheet; (3) aluminium framed secondary glazing; and (4) aluminium framed low emissivity (low-E) secondary glazing. Models of 'typical' New Zealand homes created in the ALF building thermal simulation programme were used to explore the heating energy savings and cost benefits provided by the different secondary glazing systems in a range of locations. Of the tested products, the low-E secondary glazing produces the largest cost-benefits. At current energy and material costs, secondary glazing was found to not be a financially viable solution in warmer climates such as Auckland. In cooler climates such as Christchurch and Dunedin, secondary glazing was found to be a cost effective retrofit alternative for existing single glazed homes</p>

scholarly journals Energy Saving and Charging Discharging Characteristics of Multiple PCMs Subjected to Internal Air Flow

Fluids ◽  
2021 ◽  
Vol 6 (8) ◽  
pp. 275
Author(s):  
Ahmed J. Hamad
Keyword(s):  
Phase Change ◽  
Energy Saving ◽  
Air Temperature ◽  
Temperature Control ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Heating System ◽  
Air Heating ◽  
Room Model ◽  
Model Temperature

One essential utilization of phase change materials as energy storage materials is energy saving and temperature control in air conditioning and indirect solar air drying systems. This study presents an experimental investigation evaluating the characteristics and energy savings of multiple phase change materials subjected to internal flow in an air heating system during charging and discharging cycles. The experimental tests were conducted using a test rig consisting of two main parts, an air supply duct and a room model equipped with phase change materials (PCMs) placed in rectangular aluminum panels. Analysis of the results was based on three test cases: PCM1 (Paraffin wax) placed in the air duct was used alone in the first case; PCM2 (RT–42) placed in the room model was used alone in the second case; and in the third case, the two PCMs (PCM1 and PCM2) were used at the same time. The results revealed a significant improvement in the energy savings and room model temperature control for the air heating system incorporated with multiple PCMs compared with that of a single PCM. Complete melting during the charging cycle occurred at temperatures in the range of 57–60 °C for PCM1 and 38–43 °C for PCM2, respectively, thereby validating the reported PCMs’ melting–solidification results. Multiple PCMs maintained the room air temperature at the desired range of 35–45.2 °C in the air heating applications by minimizing the air temperature fluctuations. The augmentation in discharging time and improvement in the room model temperature using multiple PCMs were about 28.4% higher than those without the use of PCMs. The total energy saving using two PCMs was higher by about 29.5% and 46.7% compared with the use of PCM1 and PCM2, respectively. It can be concluded that multiple PCMs have revealed higher energy savings and thermal stability for the air heating system considered in the current study.

scholarly journals A Study of Developing a Prediction Equation of Electricity Energy Output via Photovoltaic Modules

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1503
Author(s):  
Minsu Kim ◽  
Hongmyeong Kim ◽  
Jae Hak Jung
Keyword(s):  
Experimental Data ◽  
Real Time ◽  
Air Temperature ◽  
Temperature Difference ◽  
Prediction Accuracy ◽  
Prediction Equation ◽  
Energy Output ◽  
Photovoltaic Modules ◽  
Mean Error ◽  
Pv Module

Various equations are being developed and applied to predict photovoltaic (PV) module generation. Currently, quite diverse methods for predicting module generation are available, with most equations showing accuracy with ≤5% error. However, the accuracy can be determined only when the module temperature and the value of irradiation that reaches the module surface are precisely known. The prediction accuracy of outdoor generation is actually extremely low, as the method for predicting outdoor module temperature has extremely low accuracy. The change in module temperature cannot be predicted accurately because of the real-time change of irradiation and air temperature outdoors. Calculations using conventional equations from other studies show a mean error of temperature difference of 4.23 °C. In this study, an equation was developed and verified that can predict the precise module temperature up to 1.64 °C, based on the experimental data obtained after installing an actual outdoor module.

scholarly journals Thermal Performance of Single-Story Air-Welled Terraced House in Malaysia: A Field Measurement Approach

2020 ◽  
Vol 13 (1) ◽  
pp. 201
Author(s):  
Pau Chung Leng ◽  
Gabriel Hoh Teck Ling ◽  
Mohd Hamdan Ahmad ◽  
Dilshan Remaz Ossen ◽  
Eeydzah Aminudin ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Thermal Performance ◽  
Field Measurement ◽  
Natural Ventilation ◽  
Residential Buildings ◽  
Wet Bulb Globe Temperature ◽  
Natural Lighting ◽  
Ventilation Performance ◽  
Globe Temperature

The provision requirement of 10% openings of the total floor area stated in the Uniform Building By-Law 1984 Malaysia is essential for natural lighting and ventilation purposes. However, focusing on natural ventilation, the effectiveness of thermal performance in landed residential buildings has never been empirically measured and proven, as most of the research emphasized simulation modeling lacking sufficient empirical validation. Therefore, this paper drawing on field measurement investigates natural ventilation performance in terraced housing with an air-well system. The key concern as to what extent the current air-well system serving as a ventilator is effective to provide better thermal performance is to be addressed. By adopting an existing single-story air-welled terrace house, indoor environmental conditions and thermal performance were monitored and measured using HOBO U12 air temperature and humidity, the HOBO U12 anemometer, and the Delta Ohm HD32.3 Wet Bulb Globe Temperature meter for a six-month duration. The results show that the air temperature of the air well ranged from 27.48 °C to 30.92 °C, with a mean relative humidity of 72.67% to 79.25%. The mean air temperature for a test room (single-sided ventilation room) ranged from 28.04 °C to 30.92 °C, with a relative humidity of 70.16% to 76.00%. These empirical findings are of importance, offering novel policy insights and suggestions. Since the minimum provision of 10% openings has been revealed to be less effective to provide desirable thermal performance and comfort, mandatory compliance with and the necessity of the bylaw requirement should be revisited.

Investigation of Thermal Effects in Direct Driven Hydraulic System for Off-Road Machinery

2016 ◽  
Author(s):  
Niko Karlén ◽  
Tatiana Minav ◽  
Matti Pietola
Keyword(s):  
Energy Efficiency ◽  
Hydraulic System ◽  
Energy Savings ◽  
Mechanical Energy ◽  
Hydraulic Model ◽  
Energy Losses ◽  
Total Efficiency ◽  
Ambient Temperatures ◽  
Wheel Loaders ◽  
Save Energy

Several types of off-road machinery, such as industrial trucks, forklifts, excavators, mobile cranes, and wheel loaders, are set to be operated in environments which can differ considerably from each other. This sets certain limits for both the drive transmissions and working hydraulics of these machines. The ambient temperature must be taken into account when selecting the hydraulic fluid since the viscosity and density of the fluid are changing at different operating temperatures. In addition to the temperature, energy efficiency can also be a problem in off-road machinery. In most off-road machines, diesel engines are employed to produce mechanical energy. However, there are energy losses during the working process, which causes inefficiency in produced energy. For better energy efficiency, hybridization in off-road machinery is an effective method to decrease fuel consumption and increase energy savings. One of the possible methods to save energy with hybrids is energy regeneration. However, it means that the basic hydraulic system inside off-road machinery needs to be modified. One solution for this is to utilize zonal or decentralized approach by means of direct driven hydraulic (DDH) system. This paper aims to investigate a DDH system for off-road machinery by means of modelling and analyzing the effect of the temperature. In the direct-driven hydraulic system, the actuator is controlled directly by the hydraulic pump which is operated by the electric motor. Specifically, it is a valveless closed-loop hydraulic system. Thus, there will be no energy losses caused by the valves, and the total efficiency is assumed to be significantly higher. In order to examine the DDH system, a thermo-hydraulic model was created. Additionally, a thermal camera was utilized in order to illustrate the temperature changes in the components of the DDH system. To reproduce the action of the system in different circumstances DDH system was run at different ambient temperatures, and the component temperatures in the system were measured and saved for the analysis. The thermo hydraulic model was proven capable to follow the general trend of heating up.

scholarly journals Experiment Study on Performance of Air Source Heat Pump

2013 ◽  
Vol 805-806 ◽  
pp. 645-648
Author(s):  
Wei Xiu Shi ◽  
Li Sheng Pan
Keyword(s):  
Heat Pump ◽  
Temperature Difference ◽  
Heat Pumps ◽  
Outlet Temperature ◽  
Exhaust Temperature ◽  
Air Source Heat Pump ◽  
And Performance ◽  
Save Energy ◽  
C 30 ◽  
Set Up

Under the situation of energy crisis, air source heat pumps are paid more attention recently. In order to save energy, the feasibility and performance of air source heat pump are studied by experiment, and variation laws of exhaust temperature, evaporator outlet temperature and outlet presser of compressor were analyzed in this paper. Air source heat pump apparatus were set up and the experiment was during 10°C, 20°C, 30°C and 40°C. The results were as follows: exhaust temperature of compressor increases gradually with the increase of tank temperature, but the temperature difference between exhaust temperature of compressor and tank temperature becomes little; temperature difference in evaporator decreases; Compressor outlet pressure increases obviously.

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