Once in a while, a solution comes along that changes the status quo by jumping across technological barriers and providing exceptional value. And what if this product could uncap a resource to improve your bottom line and the health of your building?
HVAC systems can consume 30% of the total building energy needed in library, student union, and classroom facilities; and in laboratory and research facilities the HVAC energy consumption can be up to 60%. When one considers the data of traditional airside energy conservation measures (ECMs), simple paybacks range from low cost quick payback to capital intensive long payback. The ECMs range from simple strategies such as night setback and/or supply air reset to full air handler replacement or variable air volume from constant volume conversion. However, few ECMs deliver more than 35% savings for the entire university campus. Consider the ROIs on the projects listed below:
*After utility rebates
ROI for Selected Lab Improvements
Airside efficiency has arguably the most dramatic financial impact of any ECM when you consider on average, our airside efficiency projects have a payback of 2.5 years with an average of 38% energy reduction in buildings.
Airside Efficiency – Driving NPVs While Providing Data
The following list of energy conservation measures is taken as the average cost and savings from five recently completed Energy Service Performance Contracts (ESPC) located in the US. The spaces utilizing demand control ventilation (ECM #11 in Table 1) are primarily labs and vivarium. These type of critical spaces are high revenue producing but also energy intensive environments that consume 5x-6x energy compared to traditional office or academic space, and provide significant opportunities for increased profitability via airside efficiency improvements.
Table 1, Average ECMs cost and savings including Demand Control Ventilation (ECM#11)
Assumptions: 10 year financed term, 3.5% interest rate, 4.5% discount rate.
When you consider the NPV of the savings and the investment over the term of 10 years, the differences in NPV for the ECMs with and without demand control ventilation (DCV) are as follows:
The DCV option by far has the best savings to investment ratio of 5.22 and yields more than $31M in NPV over a 10-year term.
In our experience, owners have often applied basic strategies such as HVAC, night setback and supply air reset, so there is considerable opportunity for dramatic reduction via demand control ventilation.
Consider the following energy reduction metrics for the cancer research center, which labs were retrofitted with demand ventilation and variable air volume systems.
Table 3, Energy Savings Metrics for Lab Retrofits, for Leading Cancer Research Institution in New York, Resulting in Approximately 50% Energy Cost Reduction
Optimised Ventilation and Data Driven Analytics
In past practice, facility managers and environmental, health and safety professionals typically set these spaces at fixed rates because they did not have the means to continuously monitor air contaminants such as TVOCs, particulates, and CO2 to determine the optimal airside efficiency. Laboratory ventilation rate guidelines are usually applied as constants, with the chosen ventilation rate rarely dynamically controlled or otherwise tailored to the occupancy or conditions of the lab. This practice neither
optimises energy efficiency nor safety. Some guidelines simply recommend a range of 4 to 12 air changes per hour. The result can be excessive ventilation, and on top of that, no data driven analytics.
For example, the airside efficiency program reflected in table 3 is based on retrofitted spaces which were initially operating at fixed air change rates of 9.3 for labs and 20 for vivarium spaces. Through DCV, the air change rates were optimized and now operate safely at 6 air change rates for labs and 8 for vivarium spaces. This yields approximately 50% energy reduction for the building! Meanwhile facility managers and EH&S now have data on the operation and use of their buildings.
Healthy buildings
Airside efficiency is an ECM that goes beyond impressive energy savings- it improves the indoor environment for occupants as well. Historically commercial buildings have been ventilated with fixed amounts of fresh air and are commonly over ventilated during low occupancy and under ventilated during full occupancy. The problem with fixed rates is building occupancy is diverse and occupants require the proper amount of fresh air for healthier environments and optimal productivity. During the energy crisis in the 1970’s, building owners in that era recognized the high cost of ventilation and took matters in their own hands and limited ventilation. ASHRAE recognized this and this lead to increased fresh air requirements via ASHRAE 62.1. To go even further, USGBC recognized increased concentration of key pollutants including particles, nitrogen oxide, volatile organic compounds, and allergens affected occupant productivity and maintained that better IEQ led to a decrease number of self-reported symptoms (Joseph G. Allen, 2016). Buildings today can be challenging environments to provide proper environmental control, so why would we want to statically control fresh air delivery for buildings that are increasingly diverse?
Airside Efficiency solutions provide the flexibility required to effectively monitor the indoor environmental quality and then inform building management systems about changing conditions to properly adjust HVAC settings. The result is the right amount of ventilation for almost all types of situations. This leads to healthier buildings, more productive employees and ultimately a building that is more profitable as well.
References
Joseph G. Allen, 1. P. (2016). Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation,.
Environmental Health Perspectives, 806-812.
About the Author:
Rob Boyajieff, Strategic Account Manager, Aircuity
After spending 18 years as a merchant marine and then power industry, Rob transitioned into the field of performance contracting. During his time in that field he worked for Johnson Controls, Honeywell EMCOR and NORESCO. Rob is currently a strategic account manager for Aircuity and is in charge of developing strategic accounts and partners in Healthcare, Higher Ed, and Life Sciences markets in New York and the Southeast.
