تجزیه و تحلیل عملکرد انرژی ساختمان توسط کد شبیه سازی دینامیکی توسعه یافته در خانه: یک تحقیق برای مطالعات موردی مختلف

A novel dynamic simulation model for the building envelope energy performance analysis is presented in this paper. This tool helps the investigation of many new building technologies to increase the system energy efficiency and it can be carried out for scientific research purposes. In addition to the yearly heating and cooling load and energy demand, the obtained output is the dynamic temperature profile of indoor air and surfaces and the dynamic profile of the thermal fluxes through the building elements. The presented simulation model is also validated through the BESTEST standard procedure. Several new case studies are developed for assessing, through the presented code, the energy performance of three different building envelopes with several different weather conditions. In particular, dwelling and commercial buildings are analysed. Light and heavyweight envelopes as well as different glazed surfaces areas have been used for every case study. With the achieved results interesting design and operating guidelines can be obtained. Such data have been also compared vs. those calculated by TRNSYS and EnergyPlus. The detected deviation of the obtained results vs. those of such standard tools are almost always lower than 10%.

In the last years a significant effort in the direction of buildings energy efficiency has been promoted by governments and scientific communities [1]. From this point of view, Building Energy Performance Standards (BEPS) codes are today an irreplaceable tool for analysing the buildings thermal behaviour and for reaching their energy efficiency. Remarkable research works have been recently carried out although such argument involves a lot of researches from decades. In particular, many BEPS codes have been developed or improved including tools for new technologies for building envelope or HVAC systems. In this framework, the scientific research field regarding the dynamic prediction of the building energy demand is still today productive and current. In addition, the recent Energy Performance Building Directive (EPBD), issued by the European Union, emphasizes the need of energy performance standards and requires the certification of all the new codes developed for BEPS analysis purpose in compliance with the related standards [1]. From this point of view, the BEPS tools for the dynamic assessment of heating and cooling demands are also recommended to be tested by several validation procedures. Among them, the EN 15625:2008 [2] and BESTEST [3] ones are adopted by international and/or legislative organizations [4] and [5]. Regarding the BEPS research field, a lot of building physical, statistical and hybrid analysis models have been recently developed and/or updated. Advantages and drawbacks of such BEPS methods are highlighted by detailed literature reviews [6] and [7]. Concerning the physical models many of them have been recently implemented in suitable computer codes for professional and/or scientific scopes [8], [9] and [10]. They include simplified and complex detailed simulation tools. In the simplified ones, lumped capacitance methods, response factor methods, conduction transfer functions methods and finite difference methods are taken into account [11], [12], [13], [14], [15] and [16]. Complex tools are based on computational fluid dynamics approaches [17]. In several cases, these methods have also been combined [11], [13], [18], [19] and [20]. Generally, the selection criteria for choosing among alternative physical methods to be adopt and developed basically depends on the complexity of the occurring building phenomena that have to be investigated, as well as on the fidelity and the accuracy of the dynamic simulation of the building’s response. Nowadays, thanks to the more powerful computers, detailed dynamic simulation models for whole building-HVAC system performance analyses are available. Through such BEPS tools the system behaviour in terms of energy use for heating, cooling, lighting, etc., as well as building indoor air and surfaces temperatures, can be predicted for the whole year, for a single season or for few hours. Some of these tools are also commercialised [8], [21], [22] and [23]. A summary about assumptions, features and limitations of such BEPS standards are reported in [24], [25] and [26]. Although all these tools are capable of a high level of flexibility, recently many new in-house BEPS codes have been developed mostly for research scopes. In many of them, the thermal Resistance Capacitance (RC) network approach is still today widely adopted [25]. It must be said, almost all these new in-house tools deal with the simulation of building temperatures and sensible energy demands, while very few models include the moisture analysis too [13] and [19]. Building-HVAC system simulation standards address many different specific application areas in the field of building physics. From this point of view, because of the high amount of variables, some discrepancy between results of the models can be obviously observed [7]. Therefore, depending on the occurring physical phenomenon that has to be investigated, specific in-house codes are more and more developed. As an example, in [27], [28] and [29] in order to analyse the effect of the spatial distribution of the heat capacity on the heat flux through the building envelope elements, codes based on the finite difference method have been recently presented. Here, a high number of thermal capacitances is taken into account by a distributed parameters model, although many reduced order models have been widely considered also for research scopes [11], [15], [16] and [30]. In [10], the effect on building heating and cooling requirements due to the solar radiation on the building façades and the incoming solar flux distribution are studied through improved methodologies based on thermal networks methods. In addition, the research effort in the building energy saving field led to investigate a lot of new building envelope technologies and innovative HVAC systems. They are often supported by renewable energies or innovative control strategies, also concerning the study of real interactions between occupants and building. For this reason, new in-house codes have been developed [30], [8], [31] and [32]. In particular, in [32] in order to study the effect of the urbanization on the building energy consumption, an RC model that links the urban canopy with a building energy system has recently been developed and validated. Finally, fast growing research and development efforts in the field of the buildings energy efficiency often involves the development of suitable and flexible computer-based models for the energy performance calculation of innovative building-plant systems. From this point of view, authors have developed several building-plant simulation codes for the analysis of innovative and traditional systems, as reported in [33] and [34]. Moreover, many improvements have been developed on the adopted physical models, mainly regarding the building envelope analysis. In particular, this model has been implemented in a computer code written in MATLAB environment, which is still today a standard tool for the scientific computation [8]. In the model routine related to the building envelope performance analysis some simplifications have been adopted vs. the above mentioned commercial simulation tools, without renouncing to describe the main physical phenomena occurring in each building element. In general, the difference between the most utilized commercial software and the one developed by the authors lies in the adopted methods for the resolution of the heat transfer in the building. In particular, as explained in the following, the main differences regard the one dimensional transient heat conduction through multi-layer envelope components, the solar and long wave radiation handling into and out of the building, ventilation and infiltration treatment, daylighting control, etc. Obviously, at this moment commercial tools provide more complete user’s interface and data libraries for building elements features, weather files, etc., as reported in [24] and [26]. In this paper a new in-house developed BEPS code is presented. In particular, detailed algorithms for modelling the solar radiation, for controlling the indoor air temperature and humidity and for assessing the latent energy are here added to the original tool, presented in [33] and [34]. Some other subroutines have been modified or improved, e.g. the calculation of the convection outside a building surface and within a zone. For this reason the new tool is called DETECt 2.1. In this code, these detailed simulation models (e.g. for the assessment of the spatial distribution of the building envelope elements heat capacity, for the distribution of the incoming solar flux in high glazed thermal zone, etc.) are grouped in a unique calculation tool. Note that a similar approach is adopted also in other works where new in-house codes have been developed mostly for studying a single physical phenomenon [10], [29], [35] and [36]. Through DETECt, detailed output, also regarding building latent energy demands and indoor space humidity levels, can be dynamically calculated. Obviously, in order to analyse measures for the reduction of the building energy demands, additional computer subroutines developed for the performance simulation of any kind of building plants (HVAC systems, DHW equipment, renewable energy applications) can be suitably added to the presented code. As a result, a tool for the whole building-plant system dynamic analysis can be obtained. With the help of the presented code it is also possible to perform new and retrofit-oriented building sensitivity analyses. The latter can be performed starting from a unique generated building model, without re-entering the varied building details in the iterative simulation procedure. In particular, a specific tool allows the user to automatically apply all the different building features that have to be analyzed (e.g. number of glass layers, type of insulating and size of windows, thickness and stratification of building envelope elements, programmable thermostats as function of the occupancy scheduling, etc.). Results regarding the carried out BESTEST standard validation procedure have also been reported. Through this technique, a good accuracy of the DETECt results is always observed. Moreover, since the BESTEST procedure is referred only to a single dwelling building located in a specific climate, a new additional code to code validation test is proposed in the present paper. Here, completely new case studies concerning residential buildings, offices and stores located in different weather zones are purposely developed. The dynamic energy performance analysis of such buildings is calculated by means of DETECt and two reference standard tools (TRNSYS and EnergyPlus). The comparison among the obtained results confirms the reliability of the presented simulation model. With the results achieved of such case studies interesting information, such as yearly heating and cooling demands and dynamic profiles of indoor air temperature and humidity, building elements surfaces temperatures and thermal loads are also provided for various design and operating conditions. The authors would like to continue their scientific research regarding innovative building envelope techniques and renewable energy systems applied to buildings thanks to the presented code. The target will be also achieved suitably extending the code functionality.

In this paper a new dynamic simulation model for the building energy performance analysis is presented for research purposes. The calculation method is based on thermal Resistance–Capacitance (RC) networks solved through differential equations. In the considered calculation procedure particular attention is paid to reaching reliable results in terms of thermal loads and energy demands as well as accurate dynamic temperature profiles. The presented model is implemented in a purposely designed computer code written in MATLAB, called DETECT 2.1. This tool was validated by a standard code-to-code comparison (BESTEST procedure). The dynamic energy performance of any building can be simulated varying the related shape and orientation, construction materials, climatic zone, position, number and geometry of windows, shadows. The presented tool can be modified or updated whenever necessary. In addition, the code can be linked to additional purposely designed subroutines in order to simulate the building HVAC systems. Newest technologies for the building energy efficiency can be modelled and simulated. The DETECt 2.1 output is: thermal design sensible and latent loads, yearly heating and cooling demands, dynamic profiles of indoor air temperature and humidity. In addition, for all the building elements dynamic trends of surfaces temperatures and heat fluxes can be provided. Different case studies are developed in order to show the results obtained by the presented simulation code. In particular, for several design and operating conditions of residential, office and mall buildings, yearly heating and cooling demands have been calculated for different European and U.S. weather zones. Some results, such as calculated temperatures, humidity, sensible and latent loads have also been reported as dynamic profiles. Through this tool, suitable design guidelines and interesting physical response, as well as retrofit analyses of the examined buildings can be easily detected. These output data have been compared vs. those achieved for the same case studies by means of TRNSYS 17 and EnergyPlus 7.2. A good similarity between the DETECt results vs. those of the above mentioned reference tools is always obtained. In particular, the observed deviation are almost always lower than 10%. In the next future, with the help of DETECt, the analysis and the optimization of several innovative technologies for the building energy saving, which are not yet completely developed or commercialised, could be carried out for scientific scopes. In addition, additional modelling capabilities will be included in the code and some model refinements, such as those related to the latent load calculation procedure and to the adopted control system, could be performed.