HVAC Economizer Control for Reduced Compressor Runtime
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Solution Overview
Problem
HVAC systems in data centers consume significant energy for cooling, with economizers limited by outdoor temperature and humidity, leading to inefficient compressor usage and increased energy costs.
Innovation Solution
A control system that forecasts and adjusts temperature set points using weather forecasts and historical data to minimize compressor operation while maintaining equipment reliability, allowing for extended economizer usage and reducing energy consumption by optimizing compressor operation based on peak and off-peak demand costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HVAC system operates the compressor continuously to maintain the IT space at the static temperature set point of 68°F, then the equipment reliability is maintained at baseline level, but the energy consumption increases significantly
Solution Approach 1:
The system dynamically adjusts the temperature set point based on outdoor conditions and X-Factor requirements rather than maintaining a static 68°F set point. The control system calculates optimal set points that vary over time to achieve the same cumulative reliability effect while reducing compressor operation during economizer periods
Solution Approach 2:
The invention changes the temperature parameter from a fixed static value to a dynamic variable that is adjusted based on outdoor temperature, humidity, and X-Factor calculations. This allows the system to operate at higher temperatures during economizer mode while compensating with lower temperatures during compressor operation to maintain equivalent reliability
2Use of energy by moving object
If the economizer is used to cool the IT space without compressor operation, then energy costs are reduced, but the system can only operate when outdoor temperature and humidity are low enough to achieve the 68°F set point
Solution Approach 1:
The system changes the temperature set point parameter to allow economizer operation at higher outdoor temperatures and humidities. By calculating X-Factor based set points that are higher than 68°F during economizer mode, the system expands the environmental conditions under which economizer can operate effectively
Solution Approach 2:
The control system performs preliminary calculations of the minimum achievable X-Factor for future time periods based on weather forecasts. This allows the system to proactively plan compressor operation to supplement economizer cooling, ensuring reliability requirements are met while maximizing economizer usage
3Use of energy by moving object
If the temperature set point is raised above 68°F to extend economizer usage, then compressor operation time is reduced, but the equipment reliability may be compromised
Solution Approach 1:
The system uses X-Factor as a feedback mechanism to evaluate and adjust temperature set points. By calculating the cumulative X-Factor over time periods and comparing it to reliability targets, the control system iteratively adjusts set points to achieve the desired reliability level while minimizing compressor operation
Solution Approach 2:
The control system performs preliminary X-Factor calculations for future time periods based on weather forecasts before actually operating. This allows the system to predict whether raised set points will achieve reliability requirements and adjust the schedule of compressor operation in advance to compensate for any reliability shortfall
Data Source
AI summary
A method of minimizing compressor use in an HVAC system for an IT space includes configuring an HVAC system to cool an IT space, providing a control system to operate the HVAC system, the control system having software configured to calculate economization mode minimum achievable X-Factor for a predetermined period of time, providing at least one parameter to the control system, the at least one parameter including X-Factor history and period weather forecast(s), setting temperature set points for each forecast interval, and analyzing the temperature set points according to maximum and minimum temperature parameters for the IT space, with intervals with set points violating the maximum temperature parameter being designated as intervals for which the compressor will operate while intervals with set points violating the minimum temperature parameter are assigned the minimum temperature set point.