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Save on Winter Energy Bills Without Sacrificing Comfort

Nov 19, 2015 8:32:14 PM

For most people at this time of year, bidding farewell to autumn and preparing for winter weather can be a struggle. At 75F, we welcome the approaching cold winter air. Why? Because this is the perfect season to reduce energy costs by implementing strategies that optimize the use of outside air.

The time is now to take advantage of the 75F Outside Air Optimizer suite of products. We offer demand control ventilation (DCV) and enthalpy economizer solutions, which are strategies that leverage outside air. While both solutions are well known in the market, 75F offers a simple and affordable controller that bundles both strategies into one. Our solution also offers the following advantages based on the way we measure enthalpy, which is the combination of temperature and humidity that determines if outside air is suitable to bring into the building.

Standard economizers receive data from module installed in the RTU. Standard economizers receive data from module installed in the RTU.

1.    Other economizers offered in the market today get enthalpy data from a module installed on the rooftop unit (RTU). Should that module fail, the economizer fails. 75F, on the other hand, gets enthalpy from live weather feeds, which inform our economizer through our wireless platform.

2.     The 75F economizer solution uses our indoor temperature and humidity sensors to calculate indoor enthalpy. With an understanding of both outside and inside enthalpy, we are able to provide superior free cooling when the conditions are right.

To learn about these two strategies and how you can generate energy savings, I sat down with our Chief Evangelist, Bob French:

Bob French, Chief Evangelist at 75F Bob French, Chief Evangelist at 75F

Jane: For those who may not be an HVAC expert, what is Demand Control Ventilation?

Bob: Demand Control Ventilation, or DCV, is a strategy in which you only open the outside air damper when indoor air quality (IAQ) demands it. The value of this can be appreciated during the weather extremes experienced in a state like Minnesota. During winter time, when you bring freezing cold outside air in, it is very expensive to heat that airflow up to the heating temperature, which is usually 90 – 100 degrees. On hot, humid summer days, that outside air is very hard on your air conditioner. To resolve this costly inefficiency, we can close that outside air damper and recirculate indoor air to save energy. When indoor air quality reaches a maximum threshold of CO2, the outside air damper will begin to modulate open to the percentage necessary to achieve your indoor air quality needs.

Jane: How do you measure air quality?

Bob: We measure air quality by attaching a C02 sensor to the return air duct. This C02 sensor communicates with the 75F Central Control Unit, which then tells the outside air optimizer how much, if any, outside air should be let in.

Jane: How does the enthalpy economizer work to save you money?

Bob: While DCV is mostly a heating strategy that restricts cold outside airflow based on IAQ levels, the enthalpy economizer is a cooling strategy aimed at getting “free cooling” from the outside when conditions are right. In the seasons when you are trying to cool down a building and there is dry, cool air outside, you can utilize the cooler outside air by opening the outside air damper to let the fresh air in. We measure this airflow by enthalpy, which is a combination of the temperature and humidity of the outside air. As opposed to dry-bulb economizers which only measure the temperature of the outside air, enthalpy economizers have the ability to open the outside air damper on dry cool days and close the damper when it is too humid outside.

Jane: What differentiates the 75F system from other solutions that exist in the market today?

Bob: The first way we differentiate is in the way we collect the enthalpy information. Other economizers collect enthalpy readings from a module on the RTU itself, while we collect our information from data provided by a weather feed, which communicates to the economizer through our Internet of Things (IoT) platform. This is an advantage because outside enthalpy modules are notorious for failing within two years of installation, and when the module fails, the economizer fails. The second way we differentiate is by measuring the enthalpy of the air within the building. By being able to compare outside air enthalpy to inside air enthalpy, we can provide what we call “superior free air cooling”. The 75F Outside Air Optimizer solution combines both strategies into one, affordable controller.

If you are interested in learning more about the 75F Outside Air Optimizer solution, contact our sales team at + 1 (651) 998-4080.

Jane Kaster

Written by Jane Kaster

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