Need to reduce your EUI and unsure where to start? Below are some of the top game-changing insights to help you reach your targets.


1. The Model

  • As far as the energy modeling goes, compact designs are the most efficient configurations with less than 40% glazing. However, this would be bad for daylight and harvesting energy during the heating season by accepting sun. Keep in mind that many cases the envelope does not drive the load. Usually, it is internal loads that drive the energy use. In some cases in cold climates you may pay a penalty for not having lots of windows facing the south (northern hemisphere) or north (southern hemisphere). Generally, it is best to choose the massing based on architecture and urban design concerns. Then adapt that massing based on analysis to make it high performance. In hot climates east and west sun is not good and shading strategies will be needed. Pay attention to whether the building is heating or cooling dominated. This will help with picking your correct strategy for the envelope.

2. Envelop Tab

  • Having efficient Roofs, Wall, and Glazing insulation when your climate has seasonal temperature peaks can significantly help lower a projects EUI. Also check your Envelope Heat Capacity input as this property is related to thermal mass, and depending on your climate can be an effective passive strategy to reduce Energy use.

3. Usage and Schedule

  • Daylight and occupancy sensors are a must for net zero designs. If you are unsure whether they will be in the final design, it might be worth running an optimization to illustrate the energy savings and payback period associated with partial/full sensors in your project. If both included, It would also be safe to drop your unoccupied properties to 0.0 w/ft2. So both Lighting (Unocc. Hrs) and Appliance Use (Unoccu. Hrs) can be set at zero. 35% of your energy could be going into schedules, set-points, and lighting/equipment loads.

4. Building Systems

This applies to both new and existing buildings. If we assume your building will have a high performance and tight envelope, then you can do the following:

  • Increase Heating COP to 0.95, for an efficient building
  • Switch Fan Flow Control Factor to the Variable Speed option
  • Make the building nearly airtight by lowering Infiltration to 0.1 ac/h
  • Include an Advanced BEM System (Building Energy Management System) to operate all these measures in sync. This is one of the easiest changes and most modern systems have this by default so it should not cost more.

5. Energy Generation

  • Photovoltaic Panels (PV) and Solar Hot Water (SHW) proportionally reduces your EUI, the more you have the less energy you need to purchase. It is always better to reduce the load first before adding this strategy. However this is can be one of the mostly costly strategies to implement, so make sure to calculate the cost of your PV and optimize for a target array size.

6. Climate Analysis

  • Additionally, take into account day as sometimes free heating from the sun can make up for the heating mid and thus a less compact design can be more energy efficient with free heating and daylight sensors. Works for heating dominated climates. Adjusting the SHGC to allow more sun in can also work.

Final Thoughts

Be sure to evaluate whether these tips are realistic design strategies for your design. The effectiveness of each item varies by project. As always use simulation to check that the strategy is working. If you get unexpected results it may point to incorrect assumptions.

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