Stability is defined as a change (or lack of change) in accuracy over a period of time.
Drift is commonly used as a specification to illustrate the stability, or change in accuracy over a period of time, commonly shown as X%/year where X = a number; i.e. 0.25%/year. In this scenario, a device with a ±1% accuracy, would be expected to have an accuracy of ±1.25% (1%+0.25%) after a period of one year. Depending on the design, brand, and range of the sensing instrument, the stability can vary widely. Continue reading “What is Stability and Why is it Important?”
Most local regulations for indoor air quality are designed around ASHRAE Standard 62. This standard specifies the minimum amount of outdoor air flow into an occupied space to be between 15 to 60 CFM per person, but more commonly building regulations require 15 to 20 CFM per person. Besides actually measuring the air flow, ASHRAE also defines indoor air quality using the concentration of carbon dioxide gas in the air. Carbon dioxide is recommended to be less than 1000 PPM. When sizing the air handling unit for a building, engineers will make the design exceed the maximum occupancy in the building or space to ensure that they will always be able to meet the minimum air requirements. In most cases, buildings or mix used spaces rarely are occupied at these maximum levels, thus the amount of conditioned air supplied is usually much greater than what is required. As building owners aim to reduce energy costs and operate buildings more efficiently, wasted energy of conditioning unneeded outside air has been a good place to start. Continue reading “Energy Savings from On-Demand Ventilation”
As buildings continue to become more and more energy efficient, we continue to see updates and recommendations to building designs. For example, ASHRAE recently published an update to Standard 62.1 Ventilation for Acceptable Indoor Air Quality that covers changes to how we monitor and control humidity in occupied spaces. Continue reading “Moisture Control for Indoor Air Quality”
The current COVID-19 pandemic spread and breadth is unprecedented. Because of this, it is important that precautions are taken when reopening schools and office buildings. The question we find ourselves asking as professionals in the HVAC trade is this:
How do you return the HVAC system back to normal operations (and continued operations) during this pandemic? Continue reading “Ensuring HVAC System Safety for Reopening Schools & Office Buildings”
Proper selection and use of relative humidity (RH) sensors are important factors in designing and building a reliable, economical HVAC system. Over the years humidity control has been getting even greater attention because of its positive impact on indoor air quality (IAQ).
The importance of humidity measurement and control can mean different things depending on the application. To the museum curator, it means preserving valuable artwork and artifacts. To the hospital facilities engineer, it means a comfortable environment for the patients, as well as maintaining accurate moisture control to prevent the spread of bacteria and infection. And to the building maintenance professional, it means a reliable building automation system that reduces energy costs while increasing the comfort of its occupants. Continue reading “What to Consider When Selecting a Humidity Transmitter”