National Efficient RTU Energy Modeling
Client: NEEA, Nicor Gas, CEE
Program: Codes & Standards
Building Use: Commercial (NR New/Existing)
Year Completed: 2025
Goals: National RTU Efficiency, C&S Advocacy
Category: Codes and Standards, Efficiency Program Support, Technology Research
Project Overview
Resource Innovations and A2 Efficiency conducted nationally representative building energy modeling to quantify the potential savings of efficient packaged rooftop unit (RTU) measures across the U.S. commercial sector. Commissioned by NEEA, Nicor Gas, and the Minnesota Center for Energy and Environment (CEE), this study expanded on prior Pacific Northwest–focused modeling to inform national codes, standards, and market transformation programs. The analysis simulated 7 building types, 11 climate zones, 4 RTU HVAC system types, and up to 15 individual efficiency measures or measure combinations using EnergyPlus.
Our Role
As a key member of the project team, A2 Efficiency provided energy modeling support throughout all phases of the project, working alongside the lead contractor (Resource Innovations / Cadeo). A2's contributions included:
Developed and executed EnergyPlus simulation models (.idf) for baseline and measure scenarios across multiple building types and climate zones.
Supported measure development planning, defining EnergyPlus syntax and modeling approach for each RTU efficiency measure.
Contributed to analysis of gas packaged RTUs, packaged ASHPs with electric resistance backup, and dual-fuel packaged ASHP systems.
Collaborated on post-processing of simulation results and savings analysis workbook development.
Project Highlights
Nationally representative scope: 7 commercial building types × 11 climate zones × 4 RTU types × 15 efficiency measures.
ERV (energy recovery ventilator) identified as the highest-impact single measure for gas RTUs; Cold Climate Heat Pump top measure for heat pump RTUs.
NEEA Tier 2 measure bundle (R-12 insulation + low-leakage dampers + ERV) achieved the highest combined HVAC savings nationally.
Study results provide direct technical evidence for advocating updates to RTU test procedures and federal efficiency standards.
Findings support national program development by NEEA, Nicor Gas, and CEE targeting both gas and electric RTU market transformation.