Energy modeling is a
whole-building assessment of energy efficiency that uses computer programs for calculations.
Energy modeling is a pre-construction, whole-building assessment of energy efficiency that uses computer programs for calculations. A model of the entire building is created on a computer. That model is then run through computer simulations to show energy performance, usually for an entire year based on meteorological information.
Energy modeling accounts for all systems within a building and examines how they impact each other. For instance, while a certain lighting system may be extremely bright, it may release excessive heat that the building’s cooling system must offset in the summer months.
An energy modeling program can even incorporate data on human usage – right down to details about the heat and respiration humans expel. An energy model also includes data on local weather patterns. In this way, energy modeling helps architects understand the outcomes of their design choices.
Energy modeling at the design stage is a great decision making tool. It allows for designers to weigh the impact of design choices and material selection on building energy consumption. At the completion of the design, the energy model should reflect all the design team decisions and contain information about predicated occupancy rates and schedules.
This design stage model is used by the various green rating programs to quantify or “score” the building’s energy use. FCM Engineering has the software and experience needed to produce working energy models the meet LEED requirements which are based on ASHRAE standard 90.1.
Design stage energy modeling typically will not be accurate in predicting the actual energy use of the building. In order to have the design stage energy model accurately predict actual engineer use it will need to be “calibrated.”
This is done by comparing the building’s utility data with the energy model results and adjusting building occupancy, schedules, plug loads, equipment run times in order to match the building’s consumption. This calibration exercise must be done when the building and all its systems are verified to be operating correctly.
The calibrated energy model can then be used to assist owner’s in decision making with regards to renovations and system upgrades.
FCM Engineering can perform the post occupancy energy model calibration for owners and facility operators.
FCM Engineering performs ASHRAE level 1,2 & 3 energy audits on commercial facilities.
ASHRAE Level 1 – Walk-Through Analysis/Preliminary Audit
The Level 1 audit alternatively is called a “simple audit”, “screening audit” or “walk-through audit” and is the basic starting point for building energy optimization. It involves brief interviews with site operating personnel, a review of the facility’s utility bills and other operating data, and an abbreviated walk-through of the building. The ASHRAE Level-1 audit is geared toward the identification of the potential for energy improvements, understanding the general building configuration, and defining the type and nature of energy systems. The audit should result in a preliminary, high-level, energy-use analysis for the entire facility.
ASHRAE Level 2 – Energy Survey and Analysis
The Level-2 project starts with the findings of the Level-1 audit, and evaluates the building energy systems in detail to define a variety of potential energy-efficiency improvements. This should include the Building Envelope, Lighting, Heating, Ventilation, and Air Conditioning (HVAC), Domestic Hot Water (DHW), Plug Loads, and Compressed Air and Process Uses (for manufacturing, service, or processing facilities). This study starts with a detailed analysis of energy consumption to quantify base loads, seasonal variation, and effective energy costs. From there, the study should include an evaluation of lighting, air quality, temperature, ventilation, humidity, and other conditions that may affect energy performance and occupant comfort. The process also includes detailed discussions with the building Ownership, Management, and Occupants to explore potential problem areas, and clarify financial and non-financial goals of the program.
ASHRAE Level 3 – Detailed Analysis of Capital Intensive Modifications
Some of the system upgrades or retrofits revealed by the Level-2 audit may require significant investments of capital, personnel, and other limited resources. Before making this level of investment, the Owner’s want to have a more thorough and detailed understanding of the benefits, costs, and performance expectations. The ASHRAE Level-3 audit focuses on a “whole-building computer simulation”, where energy modeling is used to very accurately predict the way the building would respond to changes in the energy systems, whether those are major HVAC retrofits or architectural modifications to walls, windows, and roof. The ASHRAE Level-3 audit involves using a calibrated energy model (see energy modeling).