1. Green building & BIM in 21st century
The development of architecture has always accompanied the development of human civilization. From « De architectura » to digital fabrication architecture, from classicism to postmodernism, construction methods and architectural styles have gone through significant changes.
In the 21st century, the concept of Sustainable Development and Green Building emerged. At the same time, the evaluation criteria of Green buildings and the simulation of building performance gradually began to receive more and more attention around the world. And it is not a coincidence. With the development of society, people pursue a harmonious relationship between human beings and nature, as well as a balance of ecological, social and economic benefits.
Green buildings have never been a style, BIM neither, they are a trend.
“We need an energy-efficient, environmentally friendly building that provides users with a healthy and comfortable environment.” This idea must be added from the very beginning of the project idea. But how do you let others believe that this is a good idea? Building performance simulation, it is the most powerful evidence and support for these ideas and can continue to contribute to the program.
Doctor Strange has simulated 14000605 times to find 1 way to defeat Thanos. So, if someday, someone tells me to simulate a 100% real environment, I prefer to take a chance with Thanos 🙂
The city, buildings, people, environment and information around us is composed of a complex network system across time and space. Every tiny parameter affects the entire system. In the past, we were limited by the technical level. It is difficult to have time to simulate and analyze various possibilities in the initial stage of the program, and the simulation model is very different from the real building. As a result, the building performance simulation is not accurate enough. The demand is met during the simulation process, but the energy consumption of the building is still very large in the actual operation.
So, what can BIM do for building performance simulation?
2. Power Stone of the simulation
As early as the 1960s, simulations of building performance were proposed, from the simple calculation of the dynamic heat transfer of building maintenance structures to the energy conversion simulation of HVAC equipment. However, with the advancement of science and technology, many professional branches have gradually developed. For example, CFD simulates fluid motion, energy analysis using simulation software, building environment, sunshine, IDA dynamic simulation, human thermal model, and more.
So what are the building simulations we need to make to achieve a sustainable building?
Building Energy Simulation - This is the most important part of building simulation. The external maintenance structure of the building is combined with energy equipment such as HVAC electrical, and the energy consumption of the building is simulated based on the geo-meteorological data. According to the results of the simulation, the layout of the building, the form of the building, the direction of the lighting and the window opening, the design of the building can be adjusted. This way to design can let us explore more possibilities and greater potential in the project.
Building Materials and Resources Simulation - We can simulate the amount of material used. From the production of materials, transportation, construction, to the demolition of recycling or reconstruction. Simulation can accompany the resource consumption of the building's entire life cycle, as a reference to the cost and environmental pollution.
Building Water Efficiency Simulation - Water resources are also a very important part of the building. Daily water use simulation in the building, outdoor landscape irrigation water and rainwater harvesting data simulation are the three main subjects of building water efficiency simulation.
Building Indoor & Outdoor Environment Simulation - The comfort of a building is associated with many natural environmental factors. Like building interior environment, sound, light, heat, indoor air quality, building group thermal environment, sunshine, climate, wind environment and so on. These researches can also be completed by simulation.
The Carbon Footprint of Building - The carbon emissions associated with the built environment represents the dominant fraction of the total carbon footprint of society. As we seek ways to reduce human-generated carbon emissions at a cost that society will accept, buildings consistently emerge as the best opportunity.
From the above simulations, we found that the key to implementing simulations and useful simulations is to have detailed building information. In the CAD era, a wall is some spatial three-dimensional information for architects and structural engineers, but it is a thermodynamic parameter for thermal engineers. All information is separated by industry reasons. But in the BIM era, every element related to architecture has its own set of properties, such as a piece of glass, its thermal properties (thermal conductivity, thermal inertia), optical properties (colour, refractive index, reflectivity), acoustic properties. (acoustic absorption coefficient), price information (material usage, the unit price per square meter), LCA information (Life-Cycle Analyse/Life-Cycle Assessment, how much resources are consumed in the production process, how much pollution is emitted), etc. are included. All of this detailed information is shared, which provides a very reliable database for the implementation of simulation. The process of creating a BIM model is the process of collecting this information. We don't need to do the repetitive work for the simulation.
Therefore, the simulation based on BIM workflow has more comprehensive and better preparation than traditional architectural simulation workflow.
3. Collaboration
In the traditional linear working model of the construction, the building performance simulation was added later, mainly for equipment selection and energy consumption assessment. If it is found that the energy consumption is too large or the internal environment is not up to standard, it is difficult to go back and modify the plan. Because every change made by the architect will lead to the repetition of this linear process. Moreover, in the one-way information transfer process, a solution to a problem may cause joint problems in other places.
The BIM-based workflow makes the elements of the system connected, and there is no process difference between the architectural design, the construction design and the various professions. The project participants can extract the model at any stage for a more comprehensive analysis, while the BIM Manager can also stipulate the authority of each major to avoid confusion. In the process, when the professionals have comprehensively considered and analyzed the relationship between the elements in the whole system, it is often possible to solve multiple problems at the same time and achieve synergy. For example, in the design phase, the architect can work with the acoustics, thermal, and optical engineers on the position of a window, and the glass material is selected through simulation. The final solution will meet the requirements in all aspects. Through simulation, the existing problems can be found earlier, and in the later stage, as the information is enriched, the model will become more and more refined, and the simulation results will become more and more real.
From the above point of view, the most critical point of building energy consumption simulation based on BIM workflow is the data transfer between the building model and the simulation model. The current standard for data sharing and exchange, the IFC standard, contains almost all information such as architectural primitive attributes, materials and relationships. But for some energy simulation software, this information is too complicated. Redundant information may also cause the simulation time to be too long and the simulation results to be inaccurate. In fact, there is a data transfer standard gbXML specifically for building analysis. However, due to the short time of its creation, the information exchange needs to be continuously optimized. The deepening of the original model and the addition of information also need to be developed. Currently, there is relatively few supporting software.
These issues are obstacles to the efficiency of collaboration. Therefore, in the future, if we want to incorporate building energy simulation into the BIM process and achieve efficient collaboration. We need to technically achieve accurate extraction and docking of information between the two, establish a standard format for data transmission of different simulation software, optimize and improve the data. At the same time, the building energy simulation results are fed back to the design team to provide an optimized reference and truly participate in the design process.
4. From virtual to reality
Simulation is useful, but simulation is always just a simulation, and there is always a difference between it and reality. If you start to fantasize about how to move virtual to reality, you will find that BIM is the key to crossing this dimension.
If we can combine the management methods of BIM and think about the life cycle in all stages of the project, building simulation can do more than just simulate the evaluation plan at the design stage. It is able to continually calibrate the model based on the real-time data by using the feedback come from the building's operational process. Achieve sustainable control of PLM (Project Lifecycle Management). At the same time, from design, construction to operation, maintenance, renovation to demolition, energy consumption information at each stage is constantly expanding BIM Information Resource Library. This also provides big data support for the next project, which can effectively reduce the simulation error.
The emergence of BIM has established a platform for the development of building performance simulation. The model built with the BIM concept not only provides the 3D model that can be used for simulation but also provides the information needed for simulation analysis of building performance. And these data make the simulation no longer virtual, idealized, but an effective simulation, tending to the real simulation.
It can be said that BIM provides basic data support for building performance simulation, and building performance simulation also provides a great opportunity for the development of BIM.
We will eventually face a storm of change. Don't try to make an umbrella. Feel the wind and make a sail.