BIM plays an important role in creating sustainable design which results in better building. BIM can be applied to support energy performance analyses and operational practices on a project-by-project need basis. So BIM should be implemented at the initial concept stage – well before key design decisions are taken as low-energy can affect the overall design process of a building.
Throughout the life duration of a building, around 80% energy is incurred with heating and cooling of rooms and for other equipment – the outstanding 20% is associated with the production of materials, construction and demolition of the building.
Detailed simulation of energy efficiency completed in the initial stage of design will be the base task in the detailed design of exterior enclosures and building service systems, ensuring that the specified interior climate conditions and energy performance is met after the construction of the building.
If BIM is applied to the design, the usage convenience of the building (comply with the planned functions) is high although the energy consumption is as low as possible. BIM provides dynamic building simulation which facilitates the building to function as a "real world" object and to verify the progress of vital quality parameters.
BIM helps to strengthen the consistency, uniformity, and usability of forecasted energy use and energy cost results. Thus BIM provides an array of opportunities - comprehensive and precise energy estimates in advance in the design process, enhance life-cycle costing analysis, boost opportunities for measurement and verification throughout building occupation, and improve procedures for gathering lessons learned in high performance building.
BIM based energy modeling can be applied to design and building operation, facilitating an overall cutback in energy consumption. BIM provides more traditional energy modeling practices, and discover opportunities to exercise BIM to support facilities management.
BIM generates efficient basic information on a constant basis for the simulations to evaluate the emerging usage convenience and energy necessity in the quickest possible time span. The assessment of usage convenience will include the temperatures forming in rooms in summer, lighting levels with natural light, light glare, temperatures of enclosures, air flow owing to the interaction of ventilation and convection etc.
The models utilized for building simulation are brought up to date all along specification of other models of building information. In the preliminary phase much information in the models is pre-conditional. With the development of the project, they will be substituted with actual choices. The role of comparison of various options is to demonstrate the impact of one or another pre-conditional decision on the development of the final result. In the phase of the preliminary model (preliminary design) the model contains adequate amount of details, facilitating to execute and submit calculations for checking of the completion of least obligations of energy efficiency, issuing of energy compliance, and will be the base task in the comprehensive design of exterior areas and building.
In general the decisions taken all through the modeling of draft volumes have the greatest impact. As for instance the choices of compactness of the building, its orientation and facade apertures location and size have great impact on the interior climate as well as energy requirement. Therefore different decisions should be supported with sufficient thoroughness through building simulations and comparison options – justifying for example the use of smaller windows or thicker heat insulation layer in exterior enclosures.