CASE STUDY

Hospitality Case Study: Advanced Rooftop Controller Energy Savings

9/16/24

ProStar, a Crete United company, supported a hotel client’s strategy to uncover savings opportunities across their facility portfolio by applying an Advanced Rooftop Controller (ARC) to two packaged rooftop units (RTUs). Data was trended and analysis showed the ARC hardware and control strategies reduced both daily consumption and peak demand. These savings result in a two-to-three-year simple payback, reducing energy expense by up to 34%.

Project Overview

LOCATION

Georgia

APPLICATION

ARC’s on two 15-ton RTU’s

CONTROL STRATEGIES IMPLEMENTED

Opti-Run Fan Control, Economizer, DCV

SAVINGS

24%-34%, 2-3 Year Simple Payback

CHALLENGE

The hotel’s existing constant volume RTU controls are not optimal. Excessive runtime can reduce equipment lifespan, while inefficient operation can waste energy conditioning unnecessary outside air and miss out on free cooling during mild weather conditions. A solution was needed to prove the potential to optimize operation and reduce the risk of premature equipment failure.

SOLUTION

Two 15-ton RTU’s were selected for the application of ARC’s. One had 2-stage natural gas heat, the other had electric heat. During a 15-week measurement & verification period, various control strategies were enabled and disabled to gather comparative data sets and enable savings analysis.

The following control strategies were demonstrated during the evaluation period:

Opti-Run Fan Control which adjusts fan speeds to match the needs of the space and reduces fan energy.
Integrated Economizer with Advanced Changeover to reduce compressor runtime and cooling energy by maximizing the free cooling value of outside air.
Demand Control Ventilation (DCV) to limit the amount of outside air, reducing the required cooling and heating energy.

RESULTS

Even though one RTU does not have full economizer capability, the controllers are conservatively estimated to reduce energy by 24% to 34%, as much as $1,761/year per unit. While extreme temperatures were not observed during this trending period, industry standard practices were conservatively employed to develop regression models and extrapolate the data to generate annualized savings estimates. If deployed on all equipment across the portfolio, this solution could generate a significant level of energy savings and become cash flow positive in as little as two years. Advanced Rooftop Controllers provide a cost-effective way to eliminate wasted energy and extend the useful life of existing equipment without the need for heavy capital expenditure, all while ensuring IAQ code compliance and occupant comfort.