How to Interpret Your Energy Analysis

This article shows you how to “read” building analysis outputs and interpret them accurately in order to start testing relevant improvement strategies.

Some questions to ask from the onset are:

• What forces are driving energy or carbon use in my building?
• Is my current design heating or cooling dominated? i.e., Is my building experiencing high levels of heat loss and having to be mechanically heated or is my building getting too hot and having to be mechanically cooled?
• Is my building internally or externally loaded? i.e., Are appliances or lighting contributing to the high temperature levels within this design? Or are external factors such as solar gains causing overheating?
• What factors will have the largest impact on my building’s performance?

With these questions in mind, you’re now prepared to interrogate the feedback you get from your analysis tool.

Getting Started

An early stage design analysis software such as Sefaira, offers a wide variety of outputs. It also allows you to select the results you’re most interested in. In this instance, our primary concerns are the annual energy performance, annual CO2 production and the annual heating and cooling loads.

Heating or Cooling Dominated?

To pinpoint the predominant load on your design, compare the heating and cooling loads in the strategy grid to see which value is higher. In this example, a higher Annual Heating Load indicates that our design is heating-dominated. It is useful to compare the total of these two loads to the overall energy use– You could discover if significant energy demand is being made by other building factors.

A Granular Breakdown of your Energy Use

With this knowledge, we’d next want to uncover what could be contributing to the high heating load. Charts within the Sefaira app offer insights into several different values such as monthly peak cooling and heating demands, water use, etc.

The Monthly Consumption chart, in particular, tells us what we’d like to know. It confirms that heating is the predominant energy issue in our design, but cooling in the summer months should also be attended to.

We can now confidently pursue a heat retention strategy in order to reduce our Annual Heating Load and achieve a greater improvement in our design.

Selecting specific strategies to pursue

Within our selection of outputs, the Monthly Heat Loss chart which helps us to understand what strategies could reduce the heating load.

It tells us that most of our losses in descending order are through conduction, ventilation and infiltration. As such, we could consider the following strategies:

Conduction: What part of the building is losing us most heat?

The Fabric Conduction Loss chart sheds light on what part of the building fabric this heat is being conducted from.

In this scenario, the culprits are the glazing, the roof and finally the walls and floor. To combat this, we could consider a different glazing ratio or test higher specification glazing. We could also increase the insulation levels in the roof, walls and floors.

Ventilation

A high-efficiency Mechanical Ventilation Heat Recovery System could significantly reduce the heat loss figures. In a previous post, adding an MVHRS with an efficiency of 70% reduced our Annual Space Heating by as much as 53%.

Infiltration: In what way can air tightness be improved?

In this case study our clients, AWW, were able to achieve a 5% saving on Annual Energy Consumption.

This approach of questioning each stage of analysis, from a broad view to the finer details of your building’s performance, is a very quick and efficient way of understanding your building and driving towards a better performing concept.