Energy modeling checklist

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What is It?

Energy modeling is an effective, low-cost way of predicting building energy use using computer software. Energy modeling software programs have the capability of simulating building energy performance using hourly climatic data (e.g. temperature, relative humidity, cloud cover, solar gain, etc.) for the specific location of the building. This type of modeling is best done very early in the design process to evaluate the energy performance of different materials, construction types, and HVAC equipment. This allows an owner to evaluate the sustainability and life-cycle cost effectiveness of these options before investing in them. Energy performance is dependent on building components such as:

  • building orientation
  • glazing percentages (window-to-wall ratio)
  • insulation of walls, roofs and floors
  • the efficiency of the HVAC equipment, and
  • functional uses of the building.

Computer simulation tools help predict and form decisions such as these while allowing the design team to learn more about how the building will react to the natural elements.

Also known as: energy simulation, building energy use simulation.

Checklist of energy modeling requirements:

This is some of the information you will need to start the energy modeling process:

Climate and weather data

  • Most locations have downloadable climate and weather data
  • Make note of any eccentricities, such as being at the edge of a large body of water

Building envelope

Plan drawings--can be schematic

  • Floor plans showing sizes of each space, including foundations
  • Site plan showing building orientation (north arrow), large trees, buildings, or other potential shading
  • Roof plans including skylights

Windows and doors

  • Elevation drawings/schematics or schedules showing sizes and locations of all windows and doors
  • U-values for all (preferred) or description of glazing and frame types and door materials

Leakage information

  • Building leakage is very difficult to determine or even estimate without extensive experience
  • Best practices would include a blower door test performed by a competent professional before and after renovation
  • An experienced professional may be able to make an approximation for leakage based on the other information about the building and visual inspection
  • For more information on how leakage is estimated visit US Department of Energy Infiltration Guidelines for Commercial Building Energy Analysis

Construction details

  • Components and materials of walls, roofs, ceilings and floors in layer-by-layer format if possible
  • Type, size, and spacing of structural members
  • Wall heights and thicknesses, floor thicknesses

Heating, ventilation, and air-conditioning (HVAC) equipment

  • System type and components with fuel types for ventilation, heating and cooling
  • Set points, number of people and occupancy schedules
  • Capacity, efficiency, areas served (including functional use such as residential, workshop, storage, etc.)
  • Same info needed for domestic hot water (DHW) if that is being modeled

Lighting and internal loads

  • Some buildings will have large internal loads (needs for extra cooling) because of lighting or other equipment
  • Certain building uses will also have higher internal loads (commercial kitchens, auditoriums, pools)

Energy modeling tips

  • The energy modeling process is iterative, be patient and thorough but realize you will not have all the information you need right away
  • Save at least a couple of versions of the model if you are doing it yourself
    • One showing existing conditions
    • One showing the greatest number of improvements possible
    • One testing various options
  • Document the process
    • Keep track of what assumptions were made, by whom and why
    • Keep a file (hard copy or electronic) showing the progress of the model and how decisions are being made
    • Keep a list of things you still need
  • Rely on experts
    • Engineers, architects, commissioning agents and contractors all have experience and knowledge of building systems
    • Cross check with these professionals to determine how accurate the modeling results are and determine basis of design
  • Don't put too much faith in the model
    • Sizing equipment and guaranteeing anything based on an energy model is very risky as the models tend to be highly inaccurate
    • Use the model to determine the relative differences in before and after, and in comparing energy-saving options

Energy modeling resources

Simulation Literacy 101]