Three Simple Steps to Better Performance

Three Simple Steps to Better Performance
 

Sefaira for SketchUp was created to empower designers to make formal decisions with performance in mind — to consider energy and daylight alongside program, context, aesthetics, and other design requirements. Here are three easy steps for using Sefaira’s real-time feedback to inform design.

Three Seconds of Setup

Architects want to focus on design — but performance analysis requires many other inputs, from lighting and plug loads to occupancy schedules, envelope properties, and HVAC efficiencies. Sefaira fills in these parameters with industry-standard values based on only three inputs: space use, location, and a code baseline such as ASHRAE Standard 90.1 or Part L. This frees you to focus on form and aesthetics.

inputs
 

Step 1: Review Energy and Daylighting

Sefaira for SketchUp provides three top-level metrics: Energy Use Intensity (EUI), Spatial Daylight Autonomy (sDA), and Annual Sunlight Exposure (ASE). 

Iteration 1
 

In addition, Sefaira automatically calculates energy benchmarks for your building type and location, so you can quickly gauge whether performance is good or bad. In my example, my energy use is well above the IECC 2012 benchmark, as well as the (even lowe

Step 1
 

My example has great daylight (100% of the space is well daylit) but poor energy use. How can I find a better balance between the two?

Step 2: Find the Culprit

What’s driving energy use in the design? Use the energy use breakdown graph to identify the largest energy user (heating, cooling, lighting or appliances). Most often you’ll want to attack the largest energy users first. In my example, cooling is the largest energy consumer.

Breakdown
 

Step 3: Identify Design Strategies

What building elements are responsible for heating and cooling loads? You can use the Heat Flows diagram to find out. This diagram shows all of the heat gains and heat losses originating with each building element, and shows how these gains and losses are contributing to your heating and cooling loads.

Red flows are “bad” — they are heat gains that add to the cooling load, or heat losses that add to the heating load. Green flows are “good” — they are heat gains that occur when heating is needed, or heat losses that occur when cooling is needed.

 

Heat Flows
 

My cooling load is driven mostly by solar gain from the South and East facades. And my heating load is driven mostly by glazing conduction. I’ll take a look at decreasing glazing on the South, East, and maybe West facades while trying to maintain good daylighting. Alternatively, I could click on any of those elements (the South Solar leg of the Sankey chart, for instance) to adjust the parameters (e.g., to improve the Solar Heat Gain Coefficient (SHGC) of the South facade).

Repeat

Design is an iterative process — and with Sefaira’s real-time analysis, so is performance feedback. Simply repeat these steps as you explore options and refine your design. The Design Changes graph shows whether you’re heading in the right direction.

Here are a few iterations on the design above:

Iteration 2
 

I reduced the amount of glazing on the South and East. This brought down my cooling load and total energy use. It also brought down my total daylighting figure. The daylighting is still pretty good, but perhaps I can improve it while further reducing energy use. The primary energy use is still cooling, still driven by South solar gains.

Iteration 3
 

I added shading and worked with the placement of the glazing to get better daylight distribution across the floor plate. My overall energy use has continued to decline, but it’s still above the IECC 2012 benchmark — and still driven by solar gains.

Iteration 4
 

Further adjustments to the shading and glazing (especially on the North and West facades, not visible in the image above) helped reduce energy use. I used high clerestory windows on the North and West facades, which provide good daylight while reducing overall glazing amounts. A few adjustments to envelope parameters (such as insulation and SHGC) allowed me to get below the IECC 2012 benchmark. This design has an EUI of 20 kBTU/ft2/yr and a sDA of 62%.

For further optimization, I can upload the model to the Sefaira web application, where I can use Strategies and Bundles and Response Curves to find additional energy savings.

About the Author

Carl Sterner

Carl is an architect, sustainability evangelist, and an avid storyteller. He applied these skills as Product Manager, Marketer and Technology Evangelist to help build Sefaira until its acquisition by Trimble. He now serves as the Director of Design and Sustainability at a design firm.

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