Effects of thermal control and of passive solar elements on the dynamic behaviour of a building

The design of a building must take into account its dynamic thermal behaviour. In this paper, we model the building as a thermal network and discuss the equivalent passive solar elements. We then discuss a modular computer program able to calculate the dynamic thermal behaviour of the building, the effects of overheating, the saving due to thermal control and the fraction of the load satisfied by passive solar elements.     

Analytical Simulation of the Passive Solar System

The computer simulation is a useful tool for heat transfer analysis of the passive solar systems especially in preliminary performance evaluation, implementation, and/or optimization of the system configurations in the course of the development and constructive design.

The present article describes advantages and conditions of an application of the simulation scheme to the passive solar system analysis, along with design criterion and requirements for analytical heat transfer models for the passive solar system simulations.

A state-of-the-art program, ESPAR, used for the simulations, has been developed for the elementary heat transfer analysis of the passive solar systems constructed as a part of a single room residential building, and formulated around a finite differential heat conductive model combined with typical passive solar system submodels.

Analytical results by ESPAR for the direct gain system with sensible or latent heat storage wall and Trombe wall system are presented comparatively with measured results.     

Numerical simulation and sensitivity analysis of lattice passive solar heating walls

A lattice passive solar heating wall (LPSHW) can remarkably improve the heating performance of passive solar heated buildings. Many parameters affect the thermal performance of the LPSHW so that it is not realistic to scrutinize the thermal performance of the LPSHW experimentally. This paper develops a three-dimensional transient heat transfer model of the LPSHW, based on which a computer simulation program is developed in language. The model predictions agree quite well with experimental data. The program can be used to simulate and evaluate the transient thermal performance, to analyze the sensitivity and the effect of climate, and to optimize LPSHW structural parameters. Hour-by-hour computer simulations are run with the program to analyze the sensitivity of a variety of parameters of the LPSHW. The calculations are rerun many times with structural parameters changed one at a time so that the effect of the changed structural parameter on the thermal performance of the LPSHW can be assessed. From the sensitivity analysis, the optimum configuration is thus obtained. The comparison between the LPSHW and the Trombe wall is made thereafter. Under the chosen conditions, thermal efficiency is 30.2% for the LPSHW and 22.6% for the Trombe wall.     

被动式太阳房的通用模拟程序

设计了被动式太阳房的通用数值模拟程序ＦＸＤ－ＰＡＳＯＬ。该程序可直接用于直接受益式，Ｔｒｏｍｂｅ墙式，花格墙式被动太阳房以及它们的任意组合系统的瞬态热工性能模拟，灵敏度分析气象参数变化影响的分析、设计参数最佳化研究以及系统的性能评价等。     

Thermal simulation of a passive solar house using a trombe-michel wall structure

Since the construction in 1967 in France of the first house with a “Trombe Wall” there has been continuing interest on a world-wide basis of the potential of passive solar systems. The integration of the absorber as part of the building structure can lead to substantial reduction in building costs of active solar systems composed of absorbers, pumps, controls, etc.; and the simplicity of the system ensures that the structure will require no more maintenance than a conventional house. The prototype of this system was built in 1967 and later designs were constructed in 1974 in the French Pyrenees. There is continuing programme of research and development into passive solar systems sponsored by the French Government through CNRS. At the University of Melbourne we have investigated over the past 2 yr the feasibility of applying such a passive solar system to Australian conditions. We have studied by computer simulation the thermal performance of the wall structure during the worst month of a Melbourne winter when equipped with a solar wall collector. This is essentially an adaptation of the French concept to conventional Australian building methods. It is interesting to note, that this type of system readily adapts itself to a modular construction approach with factory made solar walls pre-assembled and delivered complete for site installation. The solar contribution to the heating load in winter conditions appears to be of the order of 40 per cent, as predicted from the theoretical computer models and confirmed from the performance data published from the monitored French houses at Odeillo.     

An efficient greenhouse design for hot climates

Greenhouses are needed in hot climates to protect plants from excessive heat, which limits productivity, and to reduce the excessive energy and water requirements associated with controlled environment agriculture under such conditions. In Kuwait, where ambient air temperature can reach 50°C during the summer and where fresh water is scarce, a new approach to greenhouse design was used. This approach included passive, as well as active, energy conservation measures, which made the utilization of such a greenhouse economically feasible. A computer program is proposed here for greenhouse design in Kuwait, aimed mainly at reducing the cooling load in an arid climate. It takes into consideration the climate, the material and the geometry of the greenhouse. The concept is to reduce the amount of intense solar radiation received in Kuwait (infrared radiation) but to maximize the amount of the solar spectrum needed for plants, as well as control the other environmental factors.     

Computer simulation of the performance of a solar pond in the southern part of Iran

In this study a computer model of a solar pond to be built in the southern part of Iran is developed. The input to the program is the daily solar radiation, ambient temperature, evaporation rate, etc. The temperature rise of the pond for various rates of energy removal is the output of the program. A parametric study on such a computer simulation for optimization of performance of the actual solar pond is quite economical. Several computer experiments are carried out for various conditions of interest of the area around Shiraz in the southern part of Iran. Temperature rise of the bottom of the pond is calculated for different rates of energy removal. It is observed that after a few months of operation, the temperature of the bottom of the pond becomes sufficiently high to allow energy extraction from the pond. The temperature variation of the pond for different overall efficiencies of the pond under various conditions are also obtained and discussed. The response of the pond to several consecutive days of cloudiness is also studied. It is concluded that solar ponds are also reliable solar collector-storage systems for this part of the world.     

Modelling and simulation of elements for solar heating and daylighting

Through the development of highly efficient transparent insulation materials (TIM), new opportunities are appearing in the field of daylighting and passive solar space heating. The simulation program WANDSIM, developed at the Fraunhofer-Institut für Solare Energiesysteme (ISE), models the dynamic performance of three important elements for daylighting and passive solar space heating: window glazing; transparently insulated masonry; transparently insulated glass wall. Selected simulation results of each type are represented and compared under thermal and daylighting aspects. The advantages of the transparently insulated glass wall, a new combined passive space heating and daylighting system, in economy and comfort are verified.     

The result of cooling operation of Yazaki experimental solar house “one”

One of the important factors for designing solar house is to examine the most economic combination what is called optimum design between solar collector area and storage volume for the required energy demand. The result of experimentation gives the fundamental data for completing the computer simulation program that is effectively usable for designing solar house.     

Simulated and experimental performance of a heat pipe assisted solar wall

Performance was evaluated for a passive solar space heating system utilizing heat pipes to transfer heat through an insulated wall from an absorber outside the building to a storage tank inside the building. The one-directional, thermal diode heat transfer effect of heat pipes make them ideal for passive solar applications. Gains by the heat pipe are not lost during cloud cover or periods of low irradiation. Simplified thermal resistance-based computer models were constructed to simulate the performance of direct gain, indirect gain, and integrated heat pipe passive solar systems in four different climates. The heat pipe system provided significantly higher solar fractions than the other passive options in all climates, but was particularly advantageous in cold and cloudy climates. Parametric sensitivity was evaluated for material and design features related to the collector cover, absorber plate, heat pipe, and water storage tank to determine a combination providing good thermal performance with diminishing returns for incremental parametric improvements. Important parameters included a high transmittance glazing, a high performance absorber surface and large thermal storage capacity.An experimental model of the heat pipe passive solar wall was also tested in a laboratory setting. Experimental variations included fluid fill levels, addition of insulation on the adiabatic section of the heat pipe, and fins on the outside of the condenser section. Filling the heat pipe to 120% of the volume of the evaporator section and insulating the adiabatic section achieved a system efficiency of 85%. Addition of fins on the condenser of the heat pipe did not significantly enhance overall performance.The computer model was validated by simulating the laboratory experiments and comparing experimental and simulated data. Temperatures across the system were matched by adjusting the model conductances, which resulted in good agreement with the experiment.     

COSSOR—a transient simulation program for a solid absorption solar refrigerator

An algorithm for the computer simulation of a solid absorption solar refrigerator, COSSOR, is presented. The algorithm is based on a detailed transient mathematical model of the system. It is a sequential modular program which consists of a relatively short main program and about 50 subprograms which are called by name by the main program or other subprograms. The program is coded in QBASIC, is highly flexible, accurate and fast, and has been tested on a wide variety of personal computers. Predictions of the refrigerator performance obtained using COSSOR compare very well with experimental data over a wide range of operating conditions. It is therefore a useful tool for computer aided design, performance prediction and analysis of the refrigerator, and may find applications in other solar thermal systems. Typical predicted results for some stations are given.     

Heat and mass transfer in porous spherical pellets of CaCl2 for solar refrigeration

An algorithm for the computer simulation of a solid absorption solar refrigerator, COSSOR, is presented. The algorithm is based on a detailed transient mathematical model of the system. It is a sequential modular program which consists of a relatively short main program and about 50 subprograms which are called by name by the main program or other subprograms. The program is coded in QBASIC, is highly flexible, accurate and fast, and has been tested on a wide variety of personal computers. Predictions of the refrigerator performance obtained using COSSOR compare very well with experimental data over a wide range of operating conditions. It is therefore a useful tool for computer aided design, performance prediction and analysis of the refrigerator, and may find applications in other solar thermal systems. Typical predicted results for some stations are given.     

Simulation analysis of passive solar heated buildings—Preliminary results

Solar gains through windows, walls, modified walls, skylights, clerestory windows, and roof sections provide an opportunity to dramatically reduce the total heating energy requirements of a building. Many such passive solar heating elements are currently available to a designer presenting a large number of possible system designs. A computer simulation analysis has been employed to aid in the selection of components. The results indicate that a performance comparable to that of a conventional active solar heating system should be achievable in an optimized design passive solar heating system. The placement and type of thermal storage is crucial to good performance. Movable insulation of the window increases the performance. When used in conjunction with a conventional heating system, temperature variations in the building can be reduced to those normally experienced.     

Matlab在无源滤波装置计算机辅助设计中的应用

本文介绍了应用Matlab编程语言设计无源滤波装置计算机辅助设计软件，着重介绍如何应用Matlab的Powerlib工具箱对无源滤波装置投用后的滤波效果进行仿真，从而验证该滤波装置谐波抑制效果。弥补了以往无源滤波装置计算机辅助设计软件无法验证滤波效果的不足。并举例说明了应用该软件设计无源滤波装置的实用性。     

An analysis of solar gain through externally shaded window of buildings

The development of computer software for analyzing the solar gain through windows of buildings is presented. The program which is capable of stating the hourly values of solar altitude angles, azimuth angles and extra-terrestrial intensity is written in the BASIC Language. The main feature of the program is that it can be used to determine the hourly values of normal solar intensity and solar energy incident on windows treated with reveals, over-hangs and side-fins. Application of the software in analyzing the solar gain through windows in some experiments yield results which are as consistent as those done manually. The experiments show that in every case, reveals have the effect of reducing the incident solar intensities, and hence incident solar energy on windows. Further analysis shows that over-hangs are much more effective in shading than vertical side-fins.     

Analysis methodology, experimental investigation, and computer optimization of a passive solar commercial building in the Belgian climate

The Fondation Universitaire Luxembourgeoise (FUL) building (completed in 1986) has been selected as a Belgian candidate for participation in the IEA (International Energy Agency) Task XI project devoted to passive solar commercial buildings. Therefore, an evaluation methodology has been set up and a monitoring plan has been defined and performed. Together with this experimental investigation, intensive computer simulation work has defined an optimized design of the building. The main results show that the recorded performance can be improved to an extent of 15% energy savings, which yields a correct performance for a passive solar building in the temperate maritime Belgian climate.     

Dynamic simulation and parametric sensitivity studies on a central solar domestic hot water system

A computer simulation program for a central solar domestic heat water (DHW) system has been developed and validated by comparing it with the actual performance data obtained from a real-life system. A computer simulation language, CSMP, was used for the simultaneous solution of the differential equations describing the system. The program was developed from basic principles and defined parameters. It was utilized to study the dynamic behavior of the system and to perform parametric studies to determine the effects of various system parameters on its performance.Parametric sensitivity studies were carried out to determine the response of the central solar DHW system performance to the following parameters: flow rate of heat-exchange fluid in the solar collector loop, consumption rate in the consumer loop, start-up time (i.e., activation of the collector loop circulation pump), and storage tank capacity.The concept of consumption management is analyzed and discussed in order to emphasize the fact that solar loop productivity, both qualitative and quantitative, is not independent of load. As a corollary, we show that it is possible, when the situation allows, to maximize solar loop productivity by controlling the consumer loop consumption schedule.     

Pre-design guidelines for passive solar architectural buildings in Kenya

Analyses have been done on the climatic data to obtain physical building design specifications for various regional climatic conditions in Kenya. The main aim is to provide a general and appropriate information at strategic pre-design stages to make better use of passive solar energy in urban planning and, building design for better indoor ‘comfort’ climate and, the health and productivity of the building occupants. It utilizes a computer program, ARCHIPAK together with climatic data (for 8 year period) to get ‘comfort zones’, and ‘control potential zones’(CPZs), for nine stations representing Kenya fairly well by virtue of their geographical locations. The use of the CPZs in building design and the objectives of the pre-design guidelines are discussed for eight major provincial urban centers and the capital City of Nairobi, all with distinctive climatic conditions. Opportunities and limitations of the pre-design guidelines are also discussed.     

Design and control of hybrid solar houses using microcomputers

We describe the thermal design and control considerations for hybrid solar houses. The system typically contains a passive system, either a direct-gain or a storage-wall system, an active collector, and thermal storage. Minimum operational requirements are described. These are best implemented with computer controllers and a design example is given of a dedicated system.     

TRNSYS The most complete solar energy system modeling and simulation software

The five computer programs TRNSYS, PRESIM, TRNSED, ONLINE and PREBID have been put together into a program package which is the most complete solar energy system modeling and simulation software that is available today.