HVAC units runtime and cycling
In the regular operation of a building, at any given time, there may be a couple of assets performing in unexpected ways, signalling that they need attention. However, keeping occupants happy and safe, and preventing the day-to-day wheels from coming off is enough to keep any building operator ridiculously busy.
Background
HVACs are one of the more expensive assets a building needs to function, and how they’re used has a significant impact on each unit's lifetime. HVAC also accounts for approximately 30% of total energy use in commercial buildings in the US, most of which come from rooftop units, and disproportionately so for small commercial offices and retail stores. This makes HVAC one of the single most important building systems to analyze, as efficient use provides massive potential to reduce overall operating costs.
In an ideal state, HVAC units should automatically and consistently run on hot and cold days to maintain setpoint temperatures (less often on milder days, about 2 - 3 times/hour for 15 minutes apiece). When a unit runs in lengthier cycles, it uses less energy, keeps occupants comfortable, and causes a lot less wear on the machine.
Conversely, units that turn on / off (i.e. cycle) frequently to maintain temperature unnecessarily consume far more energy, drastically increase the rate of repairs and degradation of the unit’s lifetime, struggle to dehumidify the air and provide a less consistent environment for occupants. ‘Short cycling’ can happen for various reasons, most of which go unnoticed and are avoidable (e.g. clogged filter, refrigerant leak, oversized unit, mechanical issues). On the other side of the spectrum, an HVAC that never stops running also signals the unit is working harder than it’s designed to and needs attention (e.g. unreasonable setpoint on thermostat, undersized unit).
What's new
Rather than roll a truck to run a one-time analysis on each unit’s performance, or install high-cost probes into every machine, the magic of modern technology helps operators produce the same answers at a significantly lower price point.
Place an inexpensive battery-powered temperature sensor into each unit’s air vent, and forget it. Solve™ continuously monitors the real-time data, using heuristics to determine when a unit is running, when it cycles, and at what rate. With these measurements, Solve reports on the relative performance of all HVACs.
This makes it easy for building operators to spot the outliers amongst their units 一 which are short cycling (or running non-stop), which are malfunctioning, and which are simply heating when they should be cooling. In doing so, Solve eliminates the pre-existing lag time it takes for a human to identify a problem while providing remote temperature information previously only available on a room’s thermostat.
Building operators can then proactively take informed action to offset energy waste, machine degradation and uncomfortable occupant conditions, get ahead of major mechanical issues, and eliminate unnecessary services during routine HVAC maintenance.
Implement this solution
Place a small battery-powered wireless sensor in each area to be monitored. Connect a LoRaWAN gateway to your local network (similar to a Wifi router).
The sensors send raw environmental data through the LoRaWAN network to Solve™, where it's decoded, assessed for alerting conditions, and saved for reporting.
| One-time price | |
|---|---|
| LoRaWAN gateway | $139 |
| Hardware sensor | $40-$80 each |
| Installation | $0 |
Your existing (non-technical) staff typically does the onsite installation of the gateway and sensors. Solve includes free onboarding and support.
| Monthly price | |
|---|---|
| Solve Core | $109 |
| Each registered user | $39 |
| Each monitored point | $6 |
| Maintenance | $0 |
Solve™ is a subscription, and the total price is based on the number of active users and monitored points. Solve Core includes the use of the Solve CRM/ticketing apps, IoT cloud hosting and management, security, awesome support, third-party integrations and free updates.
All recurring prices are broken down monthly, but in many cases they may be billed annually.
Once the LoRaWAN network and Solve accounts are in-place additional solutions can be layered in by simply installing more "sensors" and enabling the corresponding "monitored points".
Details
Risks of ‘short cycling’ HVACs:
- Hard on the condenser, compressor and filters, shorter lifetime and more frequent repairs
- Unnecessarily higher energy bills
- Trouble dehumidifying spaces
- Less comfortable oscillating temperatures
- Oversized and more costly HVAC equipment
- Unaddressed problems that could lead to equipment failure or downtime
Woradechjumroen, Denchai, Yu, Yuebin, Li, Haorong, Yu, Daihong and Yang, Huojun. “Analysis of HVAC System Oversizing in Commercial Buildings through Field Measurements.” Energy and Buildings 69 (February 2014): 131-143.