Page 33 - Climate Control News Magazine March 2021

Energy Cost Reduction & Monitoring
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fices that had a dynamic behaviour (changing from occupied to unoccupied on a rapid basis), from a specific time in the afternoon (e.g. 1 PM) the unit would get an “off” signal. If the users are still in the office and wish to operate the unit, they can do it from their local RC. If they left earlier for a meeting outside, that would save us energy. Af- ter a certain hour, we will turn all the units off and prohibit the local operation to verify the system will stay off after the working day.
TIMER OPTIMISATION
Some of the newer systems have this feature embedded in them, nevertheless, even if we don’t have this feature, we can save energy with a little trial and error. As you can see from the graph, there is a peak at the beginning of the day as most of the indoor units start working at once and demand for cooling is high. In relation to our electric program with our supplier, this peak might be at a very high rate we would like to avoid. The way to overcome it is to gradually start the system before the working day begins. This way the heat load is low, and it will be eas- ier and cheaper to achieve the desired tempera- ture at the desired time. How much earlier var- ies between projects which is why trial and error is necessary.
SENSOR USE
There are times when energy is wasted by pro- viding HVAC support in unoccupied spaces. This may be due to forgetting to turn it off or un- derestimating absence time.
Connecting an IR sensor that turns off the unit af- ter 15 minutes will save you money. In research con- ducted by the Bavarian Environment Agency, they concluded that this single method can result in sav- ings as high as 30 per cent compared to regular use.
SETBACK
As we need to reduce the night load some of the systems have a Setback function. This function will keep the conditions in the building in spe- cific areas, creating boundaries. The system will remain off as long as the temperature stays be- tween the boundaries we set. Once the bounda- ries are crossed, the system will reset itself to stay within the boundaries that have been set.
“IN THE AGE OF COVID-19 BUDGETS ARE TIGHT SO PROJECTS NEED TO BE COST-EFFECTIVE.”
For example, in the summertime, we can de- cide that the maximum temperature in the build- ing should not exceed 28 degrees. As long as the temperature inside the building stays below 28 degrees the system will stay dormant. Once the temperature goes above 28 the system will take steps to stabilise the cooling in that specific area.
PEAK CUT CONTROL
Depending on your program, high load during the day can come at great cost. Peak cut con-
trol enables you to limit energy consumption to a specific value e.g. 70 per cent from the reg- ular maximum energy consumption for a cer- tain time.
By using this method some energy companies even provide incentives. We can apply this prin- ciple by increasing the water target temperature in chillers. By doing this, the trade-off may be im- proved occupant comfort.
INDOOR UNIT CONTROL
To complete peak cut control, we might want to change the indoor unit’s settings to deal with the capacity drop. There are a few methods available. One option is to increase fan speed. In some of the systems with this embedded function, the system can cycle the capacity between the indoor units and compensate for comfort and lack of capacity.
SUMMARY
Even with little means, we can apply simple meth- ods to deliver big energy savings. It is also impor- tant to use the system properly by shutting doors and windows, shading high solar radiation areas and shutting the unit when leaving the room.
It is also important to ensure equipment is well maintained as faulty pumps, inaccurate thermistors and poor insulation can be costly.
A side note. Some of the newer systems have more advanced features that can produce even greater energy savings without compromising comfort. If you have a modern system, it is worth finding out what energy saving features are built-in to the system. ✺
CLIMATE CONTROL NEWS MARCH 2021
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