What is Energy Modelling?
As a building energy consultant, I find I am often explaining the term ‘energy modelling’ to homeowners and builders alike.
So, what exactly does energy modelling mean? Energy modelling is a way of predicting a building’s energy use over time. To develop an energy model, any items that influence a building’s heat gain or loss is entered into specialized computer software, then run to simulate a building’s energy use over time, provided certain assumptions. In addition, energy modelling can also consider the efficiency of the energy consumed in the building for the heating or cooling of the space as well as the hot water used by the occupants of the building.
Confused? Think about how ESPN might simulate a World Cup soccer match in FIFA19 using computer software as a means to predict the outcome of that match, or how a stock trader might use data science algorithms to predict future stock prices. Just like energy modelling, both these examples attempt to predict a future outcome. Unlike the examples above however, heat and mass transfer principles applied in energy modelling software is much more predictable than stock prices or soccer matches.
Why Energy Modelling?
I learned quickly in engineering school that what is measured and tracked can be improved upon. In many ways, engineering design is all about control. If a process can be controlled, it can be managed to perform its intended design function.
For this reason, the rise of computer simulation capabilities has increased the use of modelling and planning during the design process. For instance, simulation and prototyping has become a cornerstone in product design, and is now used extensively to reduce costs and optimize objectives. Whole building energy modelling applies this concept to buildings. Building energy consultants rely heavily on whole building energy modelling to help make decisions before construction, and also encompass thermal comfort and indoor air quality parameters for a multi-objective analysis.
Does it make more sense to upgrade your windows or install an HRV? Should you focus on envelope airtightness or add additional insulation? Since all buildings are unique, these questions can only be answered with certainty if alternatives are compared quantitatively.
The industry has recognized the importance of energy modelling. Today, many certifications require energy simulations to show compliance for both commercial and residential buildings. Popular programs such as NRCAN’s EnerGuide Rating System™, EnergyStar for New Homes™, as well as Passive House, and LEED certifications all require energy modelling to meet certification specifications.
This focus in energy quantification has also been mirrored in the new BC Building Code provincial requirements. The BC Building Code Section 9.36.5 allows compliance via energy modelling. Similarly, the new BC Step Code which is Section 9.36.6 also requires energy modelling and a blower door test (a test that measures air leakage).
With BC leading the way, there is a bright future for our built environment. After all, what is measured can be improved.