A building's energy performance depends on more than the efficiency of an individual product. Its façade, lighting, environmental systems and pattern of use work together. Energy modelling helps examine these relationships during design and compare alternatives. The value for owners and project teams is understanding why a decision changes an outcome and turning that understanding into a practical design.
What does energy modelling show?
Building energy modelling is a simulation method using geometry, construction, systems, climate and use information. It helps explore how a building may use energy under different conditions. It can examine interactions between systems rather than produce only an overall total. US Department of Energy — Building energy modelling.
Glazing selection, for example, may affect daylight, solar heat gains and conditioning demand together. Evaluating an option through a single property gives a limited picture. Defining the decision at the start makes the results easier to understand. The design team can then find the relevant comparison without searching through unnecessary detail.
The opportunity in early design
Options are easier to consider while orientation, building form, openings and the systems approach remain open. Energy analysis helps the architectural and engineering teams discuss them together. DOE also describes modelling as a tool for balancing different requirements during early design. DOE — Architectural design use case.
Not every product needs to be selected before work begins. Known information is distinguished from assumptions, and the analysis develops with the design. Early findings should not be presented as confirmed construction information. This approach shows the team which decisions remain open and what information is needed next.
What is a simple box study for?
A simplified massing model, often called a simple box, can examine early design questions using limited geometry and defined use assumptions. It helps reveal important relationships before all building details are available. LEED's integrative process also connects early energy investigation with design decisions. USGBC — Integrative process guidance.
The study does not replace detailed systems design. It may provide an early comparison of façade orientations or shading options, for example. More developed project information can then support a deeper analysis. Maintaining this connection between early options and the final design makes the study useful beyond its report file.
Read results through the correct indicators
Energy use, energy cost and carbon emissions are different indicators. An improvement in one may not produce the same proportional change in another. Reports should identify the indicator being compared so that investment decisions use the right information. The effect of a design change should be explained alongside its comparison conditions.
Calculated results also differ from measured operational consumption. Actual use, weather and operating settings influence consumption. Where measured information is available for an existing building, its relationship to the analysis scope should be examined. A new-building design comparison explores alternatives under defined conditions; it is not a fixed promise about future bills.
Design studies and certification calculations
Investigating a design option and demonstrating certification compliance are different objectives. Certification calculations follow the relevant rules for baseline and proposed designs. Design studies compare options suited to the team's question. Separating these purposes at the start helps define the expected report and information needs.
AECO provides building energy modelling as a separate technical service. Where another team leads LEED consultancy, the work can be scoped in coordination with that team. The initial discussion considers the current design stage and the decision that needs support. Analysis and reporting are defined accordingly, with deliverables and responsibilities clarified separately.