A thermal scan of a building energy model

Energy modeling is the process of creating computer simulations to analyze and predict the energy performance of buildings, systems, or processes. Some benefits to performing an energy model include:

• Deliver return on investment by finding inefficiencies and adjust systems to meet operational needs.
• Save time by delivering an early assessment on whether a building complies with energy codes.
• Reduce confusion by determining where system components such as solar and battery may be placed.

VCA Green uses specialized software tools to model the energy consumption, thermal behavior, and overall efficiency of a given system under different conditions. Energy modeling considers various factors that influence energy usage, including building geometry, construction materials, insulation levels, HVAC (heating, ventilation, and air conditioning) systems, lighting, occupancy patterns, and weather conditions.

Inputting these parameters into an energy modeling software generates a detailed simulation that estimates energy consumption, identifies energy-saving opportunities, and evaluates the impact of design changes or energy efficiency measures. Though energy modeling is often utilized to determine code compliance, models can be useful for utility bill estimation, PV sizing, benchmarking, and CUAC.

So, what’s needed for an accurate energy model? The initial inputs are:

• Building size
• Insulation levels
• Occupancy numbers
• Equipment/appliance details

Historical utility bills from previous periods are also a nice-to-have, as they help establish a baseline for energy usage. Using simulated energy consumption data, the energy model can gauge potential utility bills, considering factors such as electricity, gas, and water usage and applicable rates. The bills can then be analyzed and compared to historical bills or other benchmarks. This analysis can help identify potential energy savings, evaluate the impact of efficiency measures or equipment upgrades, and assist in budgeting or financial planning.


Adding solar to your model

An energy model can even incorporate a photovoltaic (PV) system into its calculations and simulations if the software is equipped with that capability. Any relevant equations and algorithms for calculating PV electricity generation based on factors such as solar radiation, panel efficiency, orientation, tilt, shading, and other system-specific parameters are included. The energy model analyzes the energy consumption patterns of the building or property to determine the electricity demand. It considers factors like historical consumption data, occupancy, appliance usage, and other electrical loads.

Based on the load analysis and desired objectives (e.g., offsetting a certain percentage of electricity consumption), the energy model can assist in determining the appropriate size of the PV system. It considers the available roof or land area, system capacity, expected electricity generation, and the desired level of self-consumption or grid independence. Once the PV system is sized, the energy model simulates its performance based on geographical location, solar resource data, system specifications, and other relevant factors. The model predicts the electricity generation over time, accounting for variations in solar radiation, temperature, shading, and system losses. Tacking PV sizing onto an energy model is a valuable tool for assessing PV system feasibility and benefits. This process optimizes sizing, provides insights into the system’s expected performance, and aids in financial decision-making related to renewable energy investments.



Affordable housing models

The California Utility Allowance Calculator (CUAC) is a tool to determine the utility allowances – the estimated electricity, gas, water, and trash services costs – for a given unit size and location for California affordable housing programs. These programs offer low-income individuals and families affordable rental housing options. The calculation considers various factors, including average utility usage, energy efficiency measures, and local utility rates.

Here’s a high-level breakdown of the CUAC process:

Data Collection: Gather information, such as the unit size, location (climate zone), and construction details to establish an energy consumption baseline.
Energy Modeling: Utilize energy modeling software or tools to simulate the property’s energy usage. Factors like building materials, insulation, windows, appliances, heating and cooling systems, and lighting are used to outline the energy consumption patterns.
Utility Rate Analysis: Consider prevailing utility rates for electricity, gas, water, and other services in the specific location. These rates may vary based on inputs like time of use, tiered pricing, seasonal variations.
Calculation: Incorporate the energy model results and utility rates into the CUAC. Based on that information, the calculator estimates the monthly utility costs for the affordable housing unit.

Integrating energy models into the calculation process provides more accurate and customized utility allowances for affordable housing programs. The CUAC helps ensure that the utility costs considered in rent calculations are fair and reflect actual residential energy use.

Overall, detailed energy modeling brings value to the construction team by enabling accurate prediction of energy performance, optimization of design decisions, identification of energy-saving opportunities, compliance with regulations, cost-benefit analysis, and enhanced collaboration. Energy modeling aligns with goals to create energy-efficient, sustainable buildings that reduce operational costs and positively impact the environment. Contact a VCA principal today to get your model started.

Moe Fakih, Principal

Robyn Vettraino, Principal

Contributing Writer: Albert Luu