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Building Envelope and Modeling

The building envelope, which includes the walls, windows, roof, and foundation of any building or facility, plays a key role in determining levels of comfort, natural lighting, ventilation, and how much energy is required to heat and cool a building. Unlike some other industrial processes, building envelope performance depends on the type of buildings and climate where it is located.

Whole-building energy modeling (BEM) plays an important role in evaluating the performance of existing buildings and identifying cost-effective energy efficiency measures. A building energy model attempts to capture the building geometry, construction, materials, occupancy, internal loads, lighting, and equipment. To improve accuracy, such a model can be calibrated to match measured energy consumption or utility bills. This software model of the building can then be used to estimate the building’s energy consumption and impact of various energy conservation measures (e.g. adding insulation) before making capital investments for improving the energy efficiency of a building.

Explore additional resources specific to Better Plants partners and connect with the building envelope and modeling-subject matter expert below.

Subject Matter Expert - Mahabir Bhandari

Dr. Mahabir Bhandari is an R&D Staff member in Oak Ridge National Laboratory's (ORNL) Whole Building & Community Integration group. He has more than 20 years of experience in the field of building energy performance. He is a LEED™ Accredited Professional Building Design + Construction (BD+C) and National Fenestration Rating Council (NFRC) certified simulator and has actively participated in several LEED™ and sustainability projects and contributed significantly in building energy software product developments. He received his Ph.D. degree at the Center for Energy Studies of Indian Institute of Technology, Delhi, India. Prior to joining ORNL, Mahabir worked as a post-doctoral fellow at the Mechanical and Industrial Engineering department of the University of Massachusetts, Amherst and Technical Director at DesignBuilder software, USA. In recent years, his focus has been on fenestration research, whole-building energy simulation, manual and auto-calibration, industrial energy data analysis for energy savings impact, Combined Heat and Power (CHP) deployment analysis, building energy monitoring and performance analysis and the evaluation and integration of energy-efficient technologies in buildings. He currently serves on the NFRC and Attachment Energy Rating Council (AERC) Board of Directors.

He is an American Society of Heating Refrigerating and Air-conditioning Engineers (ASHRAE) certified Building Energy Modeling Professional (BEMP). He works with ORNL’s Building Energy modeling team in developing the modules for EnergyPlus, DOE’s flagship whole building energy tool, and provides building envelope and whole-building energy modeling assistance to various programs. While working at DesignBuilder Software, as a Technical Director, he provided training and technical support for DesignBuilder Software, a compressive Graphical User interface for EnergyPlus. He also provided training for THERM, WINDOWS and OPTICS programs used for building envelope including fenestration systems modeling. He is certified as a simulator for windows attachments modeling by AERC.

You can reach Mahabir with building envelope and modeling-related questions at