Section 2: How is my building performing?

GOALS

  1. Understand how building performance analysis works
  2. Learn how you can understand and influence the performance of your building

Carrying out building performance analysis in Sefaira is an iterative, three-step process that starts early and often during your design phases. Using  real time analysis data, you continually assess how your building is performing, what is driving that performance, and what you can do to influence it.

This section will walk you through the Sefaira interface in the SketchUp plugin. With an understanding of what the interface means, you can interpret the data and analysis to get a better view of how your building is performing.

To make the most of this learning exercise, download a sample model to walk through the core training exercise:


The Sefaira Plugin

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The Performance Dashboard

The Performance Dashboard is designed to give a quick snapshot of energy and daylight performance as the design evolves. It is made up of three dials that detail your Energy Use Intensity, Energy Segments, and Daylighting performance. At a glance, you will know how much energy your project is using per year (EUI), which building factors are driving that energy use, and how much (good and bad) daylight your building is receiving.

Dial 1: Energy Use Intensity or EUI is a building’s annual energy use per unit area. It is typically measured in thousands of BTU per square foot per year (kBTU/ft2/yr or kWh/m2/yr). EUI is useful for comparing the performance of buildings across sizes, types, and locations. It can help you design buildings with low energy use, and, as a likely result, lower operating costs. The color of the dial also shows whether the building is meeting 2030 Challenge targets (when it is green) or not (when it is red). 

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Dial 2: The Energy Segments dial further breaks down the EUI into four major categories of Heating (red), Cooling (blue), Lighting (yellow) and Appliances (purple). This example shows a building in which the majority of the energy use is from heating the building.

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Dial 3: The Daylighting dial shows the percentage of floor area that is ‘well lit’ (Spatial Daylight Autonomy, shown in blue), ‘glare’ (Annual Sunlight Exposure, shown in yellow), and ‘underlit’ (shown in grey) in line with LEEDv4 metrics.

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Setting use type, location and baseline. How did performance change?

Setting up your analysis in Sefaira for meaningful performance feedback requires only three inputs;

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  1. Use Type: Is your building an office or a house? This determines your space schedule. Choose a building type of either Office, Residential, School, Healthcare or Laboratory.
  2. Baseline and Climate zone: (note that climate zones are only set for ASHRAE 90.1). Choose from either a Standard Baseline, including default ASHRAE 90.1 and Part L, or adjust the sliders to create your own custom baseline which can be recalled later on to quickly re-apply to other projects.
  3. Location: Where is your building in the world? Enter a location, Sefaira supports locations all over the world. This information helps the analysis engine pull the relevant weather files for your project.

Setting a baseline

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  1. Dropdown to use a standard baseline or create your own.
  2. Clicking on the slider will show the exact parameter value and units.
  3. Click to return to the Performance Dashboard.

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After setting those three inputs, we can see in this scenario that;

  • our office is being built in New York,
  • with an ASHRAE 90.1 for 2013 energy baseline,
  • is currently not meeting the 2030 challenge (the dial is still red).

The building has an EUI of 45kBTU/ft2/yr and is equipment dominated. We would need to look at the Gains & Losses chart to better understand why. Lastly, this design needs some attention given to improving daylighting since the area is mostly underlit.

 

 

 

 

 

 

 

 

Gains & Losses Tab: digging deeper

The Gains & Losses diagram shows which building elements are responsible for heating and cooling loads. Red flows indicate negative (bad) contribution towards either the heating (on the left) or cooling (on the right) loads. Green flows indicate positive contributions towards either heating or cooling loads.

TIP Hovering the mouse over any of the elements will allow you to see the exact values of those loads, and clicking on the elements allows you to adjust the baseline proprieties which correspond to the load.

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This Gains & Losses chart is showing our design has high heating loads due to our wall conduction. Reducing the building envelope area would be one solution to decrease the heating load. Alternatively we could decrease the load on heating by improving the insulation of the walls, i.e, the R-value or U-factor.

 

 

 

 

 

 

 

 

 

 

 

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This Gains & Losses diagram is showing our design has large loads to the cooling system due to South solar heat gains. Several different strategies could be explored to lower the loads to the cooling system:

  • Reducing the amount of glazing on these facades (a smaller glazing ratio),
  • Testing the impact of shading, and,
  • Specifying better performing windows (reduce Solar Heat Gain Coefficient).

 

 

 

 

 

 

TIP The Gains & Losses diagram automatically orders the largest gain at the top down to the smallest at the bottom.

The Guidance Tab

The Guidance tab in the Sefaira plugin pulls relevant passive design strategies together helping beginners understand building performance concepts, and focusing the expert designer on the best approaches. These strategies are culled from the 2030 Palette, an in-line repository created by the Architecture 2030 team in conjunction with the AIA.

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