Practice Exercise: Building Envelope Systems


Starting Point:

The starting point model generated an energy model with a predicted mean EUI of 74.4 kBtu.ft2/yr.


Baseline Model

Implementing the following measures yielded a predicted mean EUI of 51.4 kBtu/ft2/yr:

  • Operating schedule: 12/5
  • Roof construction: R38


Implementation of Building Envelope Measures

In order to explore the potential impact of power and lighting measures versus building envelope measures, I will modify the following measures to attempt to drive down the predicted mean EUI:

  1. Plug Load Efficiency (the equipment and appliances that draw power)
    1. Lowered the plug load efficiency to 1.0 W/Sq.ft. (46.6 EUI mean)
    2. image
  2. Lighting Efficiency (based on the efficiency of the lighting fixtures)
    1. Set the lighting efficiency to 1.9 W/sf (55.2 EUI mean)
    2. image

  3. Daylighting & Occupancy Controls
    1. Implemented Daylighting & Occupancy Controls (54.5 EUI mean)

Even after implementing these energy conservation measures, I was unable to achieve a mean EUI of 54 or less. Therefore, I will implement more measures.

  1. Implement greater lighting Efficiency (based on the efficiency of the lighting fixtures)
    1. Increase energy efficiency to 1.1 W/SF (45.9 EUI mean)
    2. image

With these energy efficiency measure implementations, I was able to achieve a mean EUI of 45.9 kBtu/ft2/yr.


The Addition of Photovoltaic Panels

  1. Use the Insight Factor tiles to explore the impact of Photovoltaic Panels, varying the:
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    1. Surface Coverage
      1. I adjusted the surface coverage to 60% and my EUI mean decreased quite a bit.
      2. image
    2. Panel Efficiency
      1. I adjusted my PV panels to reflect an efficiency of 20.4% (44.4 kBtu/ft2/yr)

      c. Payback Limit (how many years you will allow for the panels to pay for themselves

      1. I modified the payback limit to a 20-year period and the EUI mean dropped significantly — 35.9 kBtu/ft2/yr.

      It is evident that in order to achieve a low EUI mean, drastic implementations must be considered within a building model, such as: the thermal properties of the building envelope, plug load efficiency, and PV panel surface coverage to name a few.