Smart Buildings


Virtjoule has been in production and in the field with a new Cellular CT device called Virtjoule Juice.  It’s a new continuous monitoring system for amperage readings used on any type of equipment electric motors or other types alternating current draw.

The new Virtjoule Cellular CT has been calibrated with the Magnelab SCT-0750 line of industrial current transducers (CT) making it both accurate and flexible for reading amperages from 0 to 3,000 amps.

With the Virtjoule Cellular CT sensor and monitoring service, you can find problems such as short or long cycles, over or under amperage conditions, and after hours operations, all of which may indicate operational problems which should be corrected before becoming expensive repairs, large utility bills, or interrupting critical business processes.

Monitor Amperage and Power

Current transducers are a special type of sensor that can not only tell if current is flowing through an alternating current wire, it can also tell you how much amperage is flowing through the wire which is useful for both fault detection and energy studies.

First dedicated cellular CT on the market

This is the first low-cost dedicated cellular CT available on the market.  Other CT products are available on the market, but they are either unconnected loggers that have to be retrieved and uploaded or are connected to gateway devices that cost well over $1,000 and don’t stand alone.

CT’s are sized and based on the electrical current used on one leg of an alternating current wire.  Sizes can go from 5 to 200 amps in the SCT-0750 line and up to 3,000 amps on other parts of the Magnelab CT lineup.

Virtjoule cellular CT with Magnelab 20 amp CT

Virtjoule cellular CT with Magnelab 20 amp CT

A Must-Have Tool for Energy Auditors, Retro-Commissioning, and Service Providers

A cellular CT will become a must-have tool.  Energy auditors, retro-commissioning specialists, and service providers are all aware of the basic usefulness of a regular handheld CT.  24/7/365 monitoring via CT gives you the ability to isolate a single component of a machine or the flexibility to find the variable energy use of an entire machine.

Virtjoule has been known for excellent fault detection capabilities and using a CT is now one more way to tap into fault detection capability in addition to understanding the energy usage of a machine.

True RMS

The Virtjoule Juice Cellular CT is a True RMS sensor.  In addition to normal sinusoidal power feeds, it can be used to accurately measure amperage on variable speed devices and other pulse width modulated machines where computing the True RMS is key to knowing the correct amperage.  Knowing correct amperage is critical to knowing how much power a machine is using and, for that matter, what parts of the machine are running.

How can you use a Cellular CT?

Cycling and hours of operation

Use the Cellular CT to pick up runtime information which includes amperage levels, cycling behavior, and hours of operation.

Failing compressors

It’s a well known fact that most aging compressors will begin to draw more amps, not only on startup, but at runtime as well.  We have seen a recent example where amperage monitoring showed that a compressor was at the end of its life and we caught the actual failure when it happened.  Monitoring amperage can give you insight into machine life expectancy issues.

Locating energy wasters

Use the Cellular CT to do sub-metering on selected units.  With power output estimates from known amperage, it’s now possible to find those energy hogging machines.

Use the Cellular CT to demonstrate how much after hours operations cost.  By monitoring the machine 24/7, you know when it is running after hours.  Because you now have amp information, along with voltage and power factor it’s now possible to closely estimate how much after hours operations are costing.  Virtjoule can help you do that.

Monitor complex behavior of individual components

Cellular CTs can be used to monitor specific electrical components of a much more complex machine.  For instance, you can know conclusively at any time how many stages of compressors are being used in a large package unit.  Also, estimating energy usage on larger and more complex machines can be very inexact because you can only estimate just exactly how the machine is used.  Rules-of-thumb break down, particularly on larger machines.  Now you can find out exactly how the machine is being used and how it’s performing.

Because amperage can be turned into power information and because we’re taking 10 second averages of amperage, you can get very accurate estimates of power usage on any electrical machine, motor, or other electrical component of a machine.

Multi-tenant situation, expense sharing

Do you have a multi-tenant situation, but sub-metering is not possible?  Use Cellular CTs to understand power use across shared machines or electrical input and allocate costs appropriately and fairly.

Comparing a standard “clamp meter” with Virtjoule Juice Cellular CT

Clamp Meter vs Cellular CT

Clamp vs Cellular CT

Available now

Virtjoule Juice Cellular CT is available now.  Call us today to discuss how Virtjoule Juice Cellular CT can help you or your clients and get your order in for this first of a kind monitoring device.

[Randy Cox - CEO and co-founder of Virtjoule - He is the software designer and analytics engineer for Virtjoule Sense sensors. He studied Chemical Engineering and Petroleum Refining at the Colorado School of Mines. You may contact Randy at: randy at virtjoule dot com] – See more at:

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Newly installed machines are often not programmed.  A client will either replace or add a machine to an existing space and the thermostat that comes with the machine is installed and no one ever programs it.  Everyone seems happy because the machine is working well and there is new cooling, but the machine is left running 24/7.  It’s as if the thermostat owners manual is tossed in the trash as the installer leaves the premises.  For a 10 ton machine running an extra 12 hrs a day, this could be a $3,000 per year oversight.


If you have thermostat controlled machines, know where the thermostat manuals are.

If you can’t find the thermostat manual, note its model number (open the thermostat if necessary) and find the thermostat manual on the web.  Most reputable makers have repositories of the original operator manual online.  Print it out, use it, and remember where you put it.

Make sure that the unit is programmed before the installer leaves the building or assign someone on your staff to get that unit programmed right away.

The days are gone when you can afford to ignore problems like this.  We live in a technology society and there is someone in your organization, young or old, capable of knowing how to do basic thermostat programming.  Find them.

Ah…A new machine

Who doesn’t love a new air conditioner?  You feel good because you might have just replaced an old with with a new unit with a really high SEER rating.  Or you may have finally taken care of a hotspot in a building and bolstered the overall cooling capacity.

It’s not unusual for clients to replace equipment expecting that their utility bill will be lower.  Normally you should see a decrease if you’re replacing a similar size machine with a newer, more efficient model.  But the devil is in the details if there isn’t enough follow through by you or your HVAC installer.

We’ve seen a few instances this summer where a client has replaced and/or added machines.  New Virtjoule HVAC monitors were added and quickly discovered the new machines were working overtime, 24/7.  No one had bothered to set the thermostat in automatic mode or to program the occupancy times and setbacks.

It’s easy to be complacent once the new machine is in and working.  The complaints stop.  Things get back to normal.

Realize that a 10 ton machine might be burning at 7.5 kW.  If that machine is running extra time then your utility bill can add up really quickly.

Let’s say that your 10 ton machine is running an extra 12 hrs a day because no one bothered to program it.  That machine could be using an extra 90 kWh / day.  An extra $8.10 / day at $0.09/kWh.  Doesn’t sound like much.  Multiply by 365 days/yr = $2,956.50.  There’s your $3,000/yr problem.

Will you be able to find someone to spend 15 minutes to program the thermostat to save you $3,000 per year?

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It’s hard to imagine where control of our indoor environments would be without the lowly thermostat. Programmable thermostats have been a mainstay of both commercial and residential heating and cooling.  But like the VCR “Blinking Twelve Problem”, the proliferation of thermostat interfaces has caused many to be completely misunderstood.  Property owners and tenants ignore the thermostat to their own detriment.  

This article discusses a client who was heating and cooling 24/7 on two of their Carrier HVAC units for a retail store in a small strip mall.  The cause was mis-programmed Carrier Debonair thermostats.  They had no idea.  Without the HVAC monitoring capability of Virtjoule, this condition may have gone unnoticed for years.

Upon properly programming the thermostat, the units are now running just 12% of the time they were running before.

Carrier is a big and trusted name in HVAC, without a doubt.  But that hasn’t solved the problem of complex programming interfaces for mere mortals.  I have a 29+ year career working with computers and the interfaces on most thermostats can still be mind boggling.  This store was using a Carrier Debonair thermostat.  Within the Debonar lineup there are no less than 10 models to choose from.  The model our client had was similar to this one:

Carrier Debonair thermostat

Carrier Debonair thermostat

Since this client was very close to where I live, I took the opportunity to go check on it myself.  First thing I did was to go on the Internet and find the owners manual for this model.  I was able to find it here:

As is often the case, I was expecting that there would be some schedule problem or perhaps a misunderstanding about what happens when the fan mode is set to “On”.  After all, we’ve seen that there is no predicting what the blower is actually doing when the heating and cooling mode is set to “Off” or even “Auto”.  We’ve seen blowers continue to run when the thermostat mode is set to “Off” and it is thermostat dependent.  Very counter intuitive, but who is going to go on the roof or hold a tissue in the air stream to notice if the blower is running after you shut down for the night?

What I found on this thermostat is that it has three different occupancy programming modes.  The first and default mode, Occupancy 1, has the unique feature that the occupancy schedule can be overridden by a light sensor.  That was a red flag to me as that means the thermostat was depending on yet another sensor which might or might not be working, rather than the building schedule that it also contains.  It could also be getting confused by other inputs like street lights through windows and start times would change radically depending on what time of year it was.  Why would you want that if the building hours are nearly identical throughout the year?

Without enough time or a good way to determine if the light sensor was working, it was clear to me that a retail establishment like this should not be depending on light to control its space.

Switching the thermostat to “Occupancy 2″ mode allowed it to be controlled by the occupancy schedule.  On this thermostat each day has occupancy times and unoccupied times.  Luckily there is a feature that allows you to copy one day to the next, but how you do that is completely inscrutable if all you had was your eyes on the thermostat.  It took some careful reading of the owners manual to figure that out.  By the way, where do you think the owners manual was on site?  I don’t know either.

Besides the occupancy mode issue, both thermostats had their time and day set wrong.  In the case of this seven day a week establishment, having the day set wrong was harmless.  But here in February, both clocks were still set to daylight saving time.

Let’s take a look at the results.  During this time the temperatures here in Colorado were temperate with daytime highs in the 40′s and 50′s and lows in the mid-20′s.  The first image is a typical daily runtime graph of one of the units before the thermostat change.  The blower was running 24/7 punctuated by cycles of heat.  There was simply no schedule on this unit and it was always running.

Runtime before thermostat change

Runtime before thermostat change

The “after” chart is one that is much easier on the eyes.  You can see some periodic runtime during the night when the setback temperature of 58 was hit.  But by late morning there was no runtime at all.  So not only was the tenant saving night time and after hours runtime, the majority of their savings was actually achieved during business hours when outside air and activity in the building was working for them.

Runtime after thermostat change

Runtime after thermostat change

 Across the two units, I was able to compute that total runtime after the thermostat change was just 12% of what it was before.  That’s what you call saving money.  Without HVAC monitoring of these units, this money would have been wasted month after month.

[Randy Cox - CEO and co-founder of Virtjoule - He is the software designer and analytics engineering for Virtjoule Sense sensors. He studied Chemical Engineering and Petroleum Refining at the Colorado School of Mines. You may contact Randy at: randy at virtjoule dot com]

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A Trane Tracker controlled office and warehouse building had a rogue schedule, resulting in a HVAC bill that was 20 percent higher than necessary for the tenant.  The building had 10 roof-top units (RTU’s), including one CRAC (Computer Room Air Conditioning) unit and nine package units.  In addition to running during normal operating hours, all nine RTU’s were showing runtime on Saturdays — when the building was unoccupied.  Neither the owner nor tenant were aware of the issue.  Simply put, these machines were operating 20 percent longer than needed which not only led to higher HVAC expense for the tenant but, ultimately, would have shortened the lifetime of the equipment, reducing the property owner’s ROI.

Although BAS (Building Automation Systems) can streamline and help control a big facility, mistakes in BAS programming are often compounded — or missed altogether — without monitoring tools.    As buildings with BAS get passed from tenant to tenant and HVAC service to HVAC service, valuable knowledge is often lost as to how the BAS and subsequent schedules were set up.  It can be tedious and expensive to recommission the building and do a full audit of schedules within the BAS.  Until there is a complaint, these sort of problem situations can drag on for months or years,  wasting energy and money.

Key Concepts

  1. Mistakes in BAS programming can be magnified across a building system, resulting in higher than necessary expenses, and still not be readily apparent.
  2. Programming of BAS, if properly done, has benefits for both the property owner and the tenant(s).
  3. Many BAS, if not most, lack the kind of internal monitoring controls that can uncover these money-wasting mistakes.
  4. BAS systems are complicated and system knowledge is often lost when new tenants move in or when HVAC services are switched.

The facility we were working on is a typical high tech office building with an attached warehouse area.  It has a total of 10 units, one Trane Voyager used as a CRAC unit and 9 other Trane Voyagers of various vintages.  All the units that we were monitoring were on the roof of the building.

BAS controlled building running after hours

Two story office, one story warehouse space

Soon after Virtjoule’s HVAC monitoring sensors were installed on the Trane Voyagers, it became apparent that there was a scheduling problem with the building.  All the units would start up on Saturday mornings at, but not exactly on, their normal weekday hour.  The slightly different start time was the first clue that an extra schedule was in the system.  Shutdowns were often at the same time as the weekday schedule for each unit.

This is a professional building with product developers and executives and featuring some manufacturing and warehouse space.  Although employees can come in on the weekend, there is no need for the building to be completely heated or cooled for just a few people.  Employees do have access to thermostats to regulate heating or cooling if they wish.

The building engineer was alerted and initially puzzled by the situation since he thought the building should be in “unoccupied mode”.  He proceeded to work carefully through the BAS system and located the rogue schedule.

Because the rogue Saturday schedules were so similar to the weekday schedule, it’s easy to see that the owners of this facility have now reduced the wear and tear on the equipment they own by one day a week — or 52 days a year!  The tenant is saving over 16 percent on their HVAC expenses (having paid 20% more than they should have) and presumably, over a longer period of time, will save on maintenance as the number of calls should decrease.

[Randy Cox - CEO and co-founder of Virtjoule - He is the software designer and analytics engineering for Virtjoule Sense sensors. He studied Chemical Engineering and Petroleum Refining at the Colorado School of Mines. You may contact Randy at: randy at virtjoule dot com]

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If you have a BAS (Building Automation System) you can’t assume that everything is always well.  Our experience has shown there can be numerous control problems with BAS systems even when staffed by full time employees (earlier blog article).  

In this article we’ll discuss problems with a Trane Tracker BAS used on a small 12,500 ft2 office and retail building in Niwot, CO.  

Without the knowledge of the building owner and operator or their HVAC service company, three out of the four Trane Voyager units were running 24 hrs a day multiple days a week, including weekends, when the building was not occupied.  The BAS programming interface was obtuse enough that even an experienced HVAC control technician failed to correct the problem on the first trip.  The problem was fixed on all four units on the second trip and our monitoring showed that the building owner would save over 5,600 hours of runtime over the course of a year.

This building is managed like many others where the building owner hires an HVAC service provider to provide varying levels of service, primarily to handle complaints and do some routine maintenance a few times a year.  The building is not large enough to justify a full time facility manager or maintenance person.

All four package units were the same Trane YCD120B3HCEB, a 10 ton package unit, installed in a small quad on the roof of this building.

After the first few weeks of monitoring, a clear picture emerged that suggested that all the units were running on flawed schedules.  Here’s a summary of what we found:

Unit 1:
Sunday through Tuesday – Unit ran 24 hrs each day
Wednesday – Saturday – 5:00 am – 11:00 pm

Unit 2:
Monday – Midnight to 7:30 pm
Tuesday – Friday – 4:30 am – 7:30 pm
Sat – on demand
Sun – 24 hrs midnight to midnight

Unit 3:
Monday – Midnight to 10:00 pm
Tuesday – Friday – Starts ranged from 3:00 am to 5:00 am with stops at 10:00 pm
Saturday – 6:00 am – 7:00 pm
Sunday – 24 hrs midnight to midnight

Unit 4:
Monday – Friday – 4:30 am – 6:30 pm
Saturday – Sunday – 3:00 am – 5:00 am and then on demand

To summarize that list, there were several units running 24 hrs per day for several days, several units with startup and shutdown times well before and after the building was occupied, and unexpected weekend runtime.

Keep in mind that this was a professional building that had some empty suites and the rest were 9-5 offices and a doctor’s office.  There was rarely any activity outside of normal business hours.

The byzantine BAS interface

This particular vintage of Trane Tracker BAS had a serial interface to the system.  The HVAC technician to had to “jack” into it with his laptop computer and was presented with a command line interface.  The building is divided into zones and groups and any particular suite would belong to both a zone and a group.

The HVAC service company for the building had only been in charge for about a year and was never asked to fully commission the building.  They had only been at the building a few times and never to fully explore the current BAS programming.  This particular BAS was old enough that their experience with it was out of date.

Everything is not as it seems

The technician discovered that there were several zones assigned to multiple groups, almost certainly caused by tenants moving in and out followed by layer upon layer of changes being made to the system.  Some of those groups had the obsolete schedules and somewhere along the line a programmer didn’t reconcile what was going on with all the zones and all the groups.  Who knows, perhaps someone did notice something amiss, but left it alone assuming the last person knew what they were doing and the problems kept stacking on.

Once we found this nest of issues we were sure that the problem would be fixed.  In the command line interface, the technician changed the schedules from things like 03:00 to –:– which was his latest understanding of how to zero out a schedule entry.

With much tedium through this interface, day by day, zone by zone, group by group, the technician dutifully found and “zeroed” out all the offending schedules by putting in –:–.  We wrapped up quite sure all was going to be well again.  It turned out it wasn’t.  Virtjoule was still detecting bad schedules, but this time it was a different set of bad schedules and all four units had the same bad schedule.  That was a disappointment, but also a clue.

The technician returned a few days later after conferring with a colleague who used to work at Trane and was an expert in these systems.  It was suggested that putting –:– to zero out a schedule entry left the Trane Tracker system assuming that it should continue whatever the last state was.  If the last state was that the building was occupied then it would go through the next schedule with the same state.  The new schedules were leaving the building in an “occupied” state at the wrong times.

The fix

Since it was not possible to tell this version of the Trane Tracker that a specific day was unoccupied, the technician had to set up very short run times on Saturday and Sunday such that the units would come on, but they would not stay on for very long.  Correcting all of the weekday schedules and double checking that the same zone did not belong to multiple groups cleaned up the other issues.  It became obvious that the new schedules were in place and correct.

Wrap up

Without the Virtjoule monitoring system, the schedule flaws programmed into this BAS would have gone unnoticed for years.  No one really knows how long it had been like that.  Left unchecked this could take years off the life of the equipment not to mention the extra utility expenses most often passed on to the tenants.

Even after a trained technician made changes, things were still not right.  Without the monitoring capability to actually know the machine was running, there would have been little resolve or patience to notice that the service call didn’t actually fix the problem.  Virtjoule not only found the problem, but it was able to verify that the problem hadn’t been fixed initially and was fixed on the second trip.

[Randy Cox - CEO and co-founder of Virtjoule - He is the software designer and analytics engineering for Virtjoule Sense sensors. He studied Chemical Engineering and Petroleum Refining at the Colorado School of Mines. You may contact Randy at: randy at virtjoule dot com]

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