Today, in 2016, we often see BAS installed in new commercial buildings with microcontroller hardware that was designed up to 10 years ago. Meanwhile, there is a growing market for cutting edge, new hobby microcontrollers outside of the BAS controls industry. Compared to commercial building microcontrollers which can cost upwards of $3,000, microcontrollers in the hobbyist market which can be as, if not more, powerful than those available commercially, cost less than a hundred dollars.

This new market is flourishing as everyday people program these microcontrollers to hack cars, build 3-D printers, and augment drone functionality. You may be unfamiliar with this technology, but soon it will be everywhere. This situation begs the following questions:

• Why are building control systems lagging so far behind the hobby controls market?

• Why does the HVAC industry accept the replacement of legacy controls with 10-year-old technology?

This article explores the current state of technology and the coming changes we should expect as the BAS controls market evolves to incorporate newer, cheaper, and faster technology under a modified paradigm. I’ll explore the significant potential for hobby microcontrollers to positively impact the BAS controls industry’s lifecycle and business model. Because many readers may be unfamiliar with the technologies available on the market, I present a comparison of a contemporary BAS controller and a typical hobby controller.

Then I’ll discuss some of the pros and cons of change from the perspective of BAS industry insiders. I cover the hardware, software, and my experience with microcontrollers in a commercial setting and as a hobbyist. I will conclude with how I see the influence these hobby microcontrollers are having on the next generation of industry professionals and how that influence will spill into our industry. My hope is that as we all learn more about what is possible, we will increase our expectations and manufacturers will respond with better products offered at lower prices.


HVAC and Hobby Controller Comparison

Despite this new microcontroller technology currently existing almost solely in the niche hobby market, it’s highly likely that soon you’ll be seeing it everywhere. This is because most of these hobby microcontrollers are complete computers capable of being used in place of a laptop if you were really motivated.

They are usually the size of a deck of cards with several networking technologies built-in. Today’s students are learning how to plan, design, wire, and program general purpose hobby microcontrollers to build robots, drones, and anything else they can imagine. Consider the potential impact this technology possesses to completely transform the HVAC controls industry. In the coming years, thousands of “digital natives” — young people who have never known a world without daily interaction with computing devices — will enter the HVAC controls industry and they will bring their technology skills and open source mindset into the HVAC controls market.

Let me introduce you to the Raspberry Pi (RasPi). It is a $50 credit card-sized Linux1-based computer with which you interface via a monitor/TV through an HDMI port and via USB keyboard and mouse. First introduced in 2012 by the Raspberry Pi Foundation as an educational tool to teach children computer science, the RasPi has already undergone three major iterations and the current version is called the Raspberry Pi 3 (RasPi3). It runs one of the most popular versions of Linux and has a 1.2GHz processor with 1 GB of RAM onboard. RasPi3 has double the capacity, longer battery life, and more USB ports than the 600Mhz Dell laptop that got me through my undergraduate computer programming degree 12 years ago. RasPi3 is so adaptable and easy to use that it is readily poised to upend the BAS industry in a good way. 

For comparison, let’s look at a current industry standard equivalent: The Tridium Java Application Control Engine (or “JACE”) controller. Tridium has revolutionized the building automation industry over the last 15 years because of their adoption of computer science trends including an open-development platform mindset. They’ve applied systems integration, interoperability, and data normalization to their Java-based2 Niagara software since its inception. They pioneered the use of Linux-based BAS computers with a small form factor to simplify system integration for the BAS industry. Tridium has been an industry leader because of this approach. In 2012 they had over 300,000 instances of their Niagara framework deployed worldwide.

As you can see in Table 1 below, these controllers have similar hardware feature sets and radically different pricing. The significant differences in current applications for both devices necessitates additional context to provide a fair comparison. First off, nobody can use a RasPi3 right out of the box in a commercial building to control their HVAC systems like you can with a JACE. The hobby microcontroller would need additional hardware, software, and testing to enable it to function like a JACE including I/O circuitry designed for HVAC industry standards, a power supply, UL rating, and a good insurance policy. While both devices are Linux computers, the JACE software has evolved over a decade and is a best-in-class programming environment for HVAC controls. Significant development would be required for a RasPi3 to match the Niagara’s ease of use and aesthetics.

The last row in the table — Operating System — is very important because it easily represents more than half the cost of implementation. That being said, it probably wouldn’t take Tridium much time to port their software over to a RasPi3 — they would just have to modify the existing Linux version of their Niagara software.

RasPi3 has the potential to have a transformative effect on the HVAC controls industry. The industry should begin to prepare itself for this transformation as technology advances and the next generation of professionals who’ve grown up using this technology enter the workforce. RasPi3 is an example of the platforms on which tomorrow’s better, more open, and better understood systems will be built.


Industry Perspectives

The hobby controller community has adopted practices that accelerate innovation including collaboration, sharing of designs and programming techniques, and software that is independent of the hardware and device manufacturers. These practices have yielded success stories like the Pebble Smartwatch (one of the first “smart” watches before the Apple Watch, it records steps, sleeping patterns, can receive text messages — and also tells time) and the Oculus Rift virtual reality headset.

This community uses standard programming languages (Python, C, Java, etc.) that are independent of hardware manufacturers, resulting in source code that runs the same across different devices. This naturally makes code review more efficient, enabling them to focus entirely on the objective of the software they’re coding and not on the semantic differences a device manufacturer might impose upon them. The lack of a common, manufacturer-independent programming language is a major pitfall in the BAS industry that the hobby microcontroller community does not suffer.

These strategies, when embraced by the building control manufacturers, will enable building operators, energy consultants, and controls programmers to optimize buildings in a more systematic and effective way. Adopting this level playing field would enable the industry to focus more on the goal of saving energy without sacrificing comfort in modern commercial buildings. This goal is one of the industry’s main sales pitches, but is never an out-of-the-box guarantee. 

The potential benefits of the BAS industry adopting a more open source approach would have ripples across the building engineering world. Engineering firms could efficiently evaluate systems years after installation since proprietary programming languages would themselves be obsolete. Building owners would benefit from more controls options in a more competitive market. Controls contractors would benefit from an information sharing model much like that of the Android operating system for smartphones by being able to share lessons learned and to reuse code across hardware platforms.

Manufacturers would benefit from hosting the forums, events, and hackathons for collaboration and information sharing within their customer base. The results of this type of collaboration would enable direct insight into the demands and struggles from their market (effectively providing a data-mining channel into their customer base). That information can be used to create software productivity solutions on top of the open source code which enables controls vendors and installers to become more efficient without sacrificing quality or openness. 

Automobiles are a great example of both hobby and industry benefiting from open source principles. Most cars are an open system of hardware where any mechanic can service most problems without being a dealer of a particular brand. Using this concept, BAS controls manufacturers could improve the market with shorter product life cycles enabling new features to be added to buildings faster and for less cost simply by making the processing components modular and always physically separating them from unchanging building input/output device wiring. This would allow the control system brains to be swapped out while leaving the sensors, actuators, and all their associated wiring and terminations in place.

Imagine a day when control cabinets are not gutted during controls upgrades because the controllers all use industry-standardized USB I/O boards over USB just like a desktop computer uses a mouse and keyboard (Figure 2). Overall, changing to an open platform and more affordable data processing equipment will significantly reduce system costs, improve access to information, increase building operational efficiency, and enable the controls market to grow using a market-driven, continuous improvement model.


Homebrew vs. Off the Shelf

I was a Tridium systems integrator from 2002 through 2014. In 2012, I became a certified Niagara developer. When I got my hands on a RasPi, I couldn’t help comparing it to the JACE in terms of application potential. The RasPi can function as a web server and store tons of trend data using any number of Linux-based databases, with the only limiting factor being the size of the micro SD card. I integrated ancillary equipment (I2C serial communications bus and Arduino5 board) to read a room temperature value from a thermistor. Figure 3 shows the layout of my set-up.

The Arduino served as an input/output board while leaving the global control functions such as trend storage and user input to the RasPi. The RasPi operated as a web server hosting a rudimentary webpage which displayed the information from the Arduino. Outputs were Form C relays wired to the Arduino’s outputs to become 24-volt6 binary outputs. Together these components enable the RasPi to function much like a crude homebrew JACE as shown in Figure 4.


Disrupting the Status Quo

The Raspberry Pi website ( provides examples of these devices being used to teach computer science at middle and high school level. Figure 5 shows the trajectory of the youngest of these current students and their technical competency as they are educated and enter the job market.

These young people are going to bring new skills and expectations to the market in seven to 10 years, and if the HVAC controls industry hopes to attract this talent, industry leaders will need to operate in ways that appeal to this new crop of programmers and engineers. If the industry continues to use closed, proprietary programming tools with expensive licensing attached, it can expect a wave of disruption as these students apply their experiences with these hobby controllers to improve HVAC controls with little upfront cost. Much like Netflix has disrupted the video rental and cable television markets that existed solidly for decades by streaming and creating new content, so too will new innovations revolutionize the way controls are manufactured and implemented. It’s only a matter of time.

In talking to college interns I hired for a summer while managing a department of 14 HVAC control programmers and field technicians, I learned that the interns were impressed with the current state of the industry and curious why there were so many controller limitations. They were completely flabbergasted by the price tag of software and controllers in the industry. Those interactions served as a warning flag that the coming wave of change is closer than I’d thought. I was inspired by these young people and their perspectives to catch the wave, instead of letting it crash against me.

Some HVAC control start-ups are beginning to ride the wave, such as a new company here in Vermont called Vermont Energy Control Systems ( that is developing commercial and industrial HVAC control systems on a hobby controller called the a BeagleBone ( So the idea of modifying these hobby microcontrollers to prototype, if not outright develop the next generation of BAS systems, is already being fleshed out by people around the country, and this work will be inherently interoperable regardless of manufacturer due to its use of standard computer programming languages.


The Next Generation

Addressing product lifecycle, openness, and cost are challenges our industry faces, and the solutions are readily available. These challenges present not only a business opportunity, but are also a call to change our industry to a model similar to Red Hat, Inc7. Their customers include Bayer AG, E-Trade, Hewlett-Packard, and Intuit.

Red Hat is a company that has successfully used the leverage from open systems technology to create software solutions from which they profit. Our industry will undoubtedly go in this direction in time because of the influence these open-sourced hobby microcontrollers will have on the next generation of our labor force. 

Current leaders in the HVAC controls industry should begin preparing for this disruptive technology and new paradigm that is on the horizon. They will need to become nimbler and more in tune with the potential of new technologies like RasPi — especially as energy efficiency demands more complicated and more capable systems. Are the major players in the industry ready for this change? Or, like Blockbuster Video, are they going to become a memory? Only time will tell, and I, for one, am excited to see what’s ahead. ES




1. Linux is one of the three major computer operating systems, the other two being Microsoft’s Windows and Unix. Linux is essentially Unix, but without the trademarking and standardization from a retail company. Linux is entirely open source while only the BSD version of Unix is considered open source.  Apple’s OS X (a version of Unix) and Microsoft’s Windows are proprietary non-open source operating systems as their source code is not freely available to the public (a defining characteristic of open source software).

2. Java is the programming language most students of computer science are taught as their first language for several reasons, but mostly because it can run on any type of PC and is simpler than previous programming languages that preceded it.

3. The JACE-8000 is priced differently per each controls contractor’s volume sales-multiplier, but I was able to get a list price at about $1,000 for the lowest capacity base model. For a higher end model, I was finding the list price tag up around $3,000.

4. Micro SD cards are the standard in portable electronic storage devices. Almost every smartphone uses them to store its user’s pictures, app data, and anything else an owner would have on their phone. You can think of them as like the hard drive in your computer. Because they’re a standardized storage device, the RasPi also uses them. Micro SD cards are also used in the JACE, as well as in digital cameras and dozens of other devices.

5. Arduino is another type of lower level, yet very powerful hobbyist microcontroller. You can find more information about it at

6. 24 volts is the industry standard alternating current voltage for controls wiring.

7. Red Hat, Inc. is a corporation founded in 1993 that provides and builds upon open source software products to the enterprise community.