How Energy Performance Modeling Using BIM Sustainable Design

“Often when you think you’re at the end of something, you’re at the beginning of something else.”
– Fred Rogers

Since the advent of last century the construction and operations of buildings and workplaces have had an extensive impact on all all three elements of Triple Bottom-line i.e they impact, People, Planet and Profit. To address these challenges, we have seen a strong upsurge from society, government and industry for the demand for sustainable design. Sustainable design is a rapidly emerging field of building design which addresses all elements of Triple Bottom-Line and brings out a win-win proposition for all participants of the construction ecosystem. Sustainable Design focuses on following key objectives

It aims to reduce the usage of vital resources like water, land, energy and other raw materials
Reduce environmental degradation brought about by buildings throughout their building life cycle
Create and operate buildings that are ergonomic, environmentally friendly and safe for people
Reduce waste generation footprint be it construction related, occupant related or demolition related

Owners and Tenants of Buildings, designers and builders are all finding it relevant that they must invest in facilities that rank high on accessibility, health and productivity while at the same time have minimal or even negative impacts on the environment, economy and society. Sustainable design is being aided by a slew of Executive Orders, Legislations, MOU’s and Sustainability Goals whose adoptions are being driven by mandates from federal agencies. To address these goals, designers and builders alike are leveraging Building Information Modeling to make sure that in terms of usability energy use and energy costs can be predicted and simulated. Energy Performance Modeling is becoming very vital in Building Information Modeling. The core advantage of Energy Performance Modeling are

Accurate energy estimates during the design process
Reliable life-cycle cost analysis using Energy Simulation
Measurement and verification of Energy usage post building occupation
Incorporating Energy Efficiency strategies for buildings

Energy Performance Modeling for designing new Buildings

Building Architecture, Selection of building materials, mechanical systems and electrical controls systems are the factors that massively impact the energy performance of a building. All major BIM software provide assessment and simulation of energy performance of a building at design stage itself. We can compare and evaluate the performance of a various materials and control systems and map them with their capital costs, operating costs and Total Cost of Ownership (TCO). This understanding of energy performance modeling at design process helps architect and technical consulting firms in understanding the life cycle implications of materials being used and help in designing energy efficient sustainable building..

Energy Performance Modeling for redesigning existing buildings

As of now, the Building Energy Performance Assessment is a standard feature in all BIM Tools and Software. They are typically used to access the impact of retrofitting existing building on improvements in energy performance and related cost savings emanating from it. Current BIM tools allow for entry of vital information data points like

Thermal zone layout of the existing building.
Weather data at that place.
Load of the building like lighting and appliances as well as that of occupants, schedules of operations and HVAC data

All these data points can easily be collated from specification drawings and other input files having such modeling data parameters. These are fed into simulation engines to calculate the energy consumption patterns of building.

Incorporating data like the geometry of the building, construction material time and thermal properties of such material from BIM were traditionally being used to drive the energy process. But at an empirical level, such exercises have often been inaccurate. This is because as of now all BIM software energy modeling is largely derived from types of generic building construction. However, for modeling energy assessment of existing buildings, such modeling using generic building construction is more often than not very inaccurate as thermal resistance of buildings diminishes owing to deterioration of buildings. The ability to import building construction thermal data from BIM can significantly improve predictability in building energy modeling process.

New Developments in Energy Performance Modeling Space

The new approach as suggested by many luminaries in academia is to leverage a collection of digital and thermal images on the basis of environmental measurements to create a 3D thermal model of an existing building that is being measured and then derive actual thermal resistance at the level of 3-dimensional vertexes. These are mapped to a schema which auto updates corresponding resistances thus enabling more accurate energy modeling of an existing building. This method of measurement will not only shorten the gap between actual data needed for energy usage simulation and architectural information already available in BIM.

Conclusion

Usage of Energy performance Modeling is going to be a standard use case for designing existing buildings and especially retrofitting existing building in future. Designers, builders and building occupants and owners that are involved in design process all agree that demolishing existing buildings and creating Greenfield building have detrimental impact on environment, people as well as on bottom-line of a balance sheet. To drive adoption it is of utmost essence to make such energy modeling a prerequisite for retrofitting process. Having it a a mandatory exercise through regulatory changes can also aid in adoption of energy modeling as a vital element of sustainable design practice.