Smart Spaces: The Benefits of Energy Harvesting IoT Sensors


Energy harvesting IoT solutions play a crucial part in not only creating better workplaces and optimizing the energy consumption of buildings, but also in significantly reducing yearly operating costs.

Over the past couple of years, we have found ourselves in almost empty office buildings with many empty desks. And even now, with employees coming back into offices with some remote work, not all employees need their own desk anymore. As a result, companies pay money for office space they don’t actually need. IoT sensors may offer ways to more efficiently use office space.

Even before COVID, a workplace was only 65% occupied due to vacations, business trips, or illness, according to Eurocres 2020. Therefore, 35% of unused space needs to be heated and ventilated, there might be lights turned on the entire day, and there might be many workplaces that nobody is using. With the clear trend towards remote work, this situation is getting even worse. With three days of working from a home office, the workplace is up to 75% unoccupied – an enormous potential for cost and energy savings.

Obviously, companies are throwing a lot of money out the window, which is now being recognized more often. According to Bürokostenreport 2019, the average operative cost of a single European workplace is 8,140 EUR ($8,552) per year, so a company with 100,000 employees can typically save 25% of their desks and 200 million EUR ($211M USD) per year. The costs of a sophisticated IoT system, on the other hand, are negligible (ROI is usually realized within two weeks).

As a result, already 60% of companies want to switch to desk-sharing models over the next couple of years, which allows them to not only save money on rent but also on furniture, heating, and lighting. In this scenario, with 25% fewer desks, this also means 25% less need for space and 25% less CO2 consumption through HVAC, an immense contribution to reducing the carbon footprint.

In order to implement desk sharing in a way that will be acceptable to employees, workplace occupancy sensors are essential to provide real-time data on the occupancy situation to the booking system, regardless of the individual behavior of each employee. Situations like the following can only be intercepted by desk sensors: forgot to check in, or the mobile app is not available (temporarily or at all), or personal check-in is not desired for reasons of privacy. To quickly find a free meeting or quiet room represents a similar situation. Sensors are required to reliably detect which workplaces are currently being used by employees and which ones are still available.

Moreover, sensors can also monitor the air quality, which contributes to a healthy and comfortable working environment. Great air quality, perfect room temperature, and a modern working environment will lead to higher productivity. Research by Lawrence Berkeley Labs (LBL) found that concentrations in classrooms and offices frequently exceed 1,000 ppm and occasionally even exceed 3,000 ppm. A study by Harvard researchers measured a 15% drop in cognitive performance scores at 950 ppm and a 50% drop at 1,400 ppm.

See also: Smart Buildings Get Smarter and Expand into Real Estate

No wires and batteries: sustainability along with money, time, and headache saving

Such an IoT solution consists of hundreds or even thousands of sensors, depending on the building size. Therefore, it is crucial to choose a system that is both cost-effective and resource-saving. Conventional wired or battery-powered solutions hold several pitfalls.

Cabling is expensive and resource-intensive. A conventional wired sensor costs about $100 for around 100 feet of cabling. For 1M square feet of smart office space, you would need around 10,000 sensors (1.5 sensors/employee, 150 sq ft/employee). By using wireless sensors, you can save 1,000 feet of wiring, 42 tons of copper (resources are increasingly limited), ten man-years of installation time, and $1 million in overall installation costs.

But it’s not only wiring that drives up costs and harms the environment. The use of batteries in wireless sensors is equally harmful and inconvenient. Firstly, batteries mostly die at the most inconvenient times, and it is not always clear which battery type is needed. Secondly, batteries are not always easy to change when sensors are installed in places that are difficult to access. Not to mention early failures that are very annoying. For this reason, service companies typically replace all batteries every 1 to 2 years, regardless of the advertised sensor lifespan.

At first sight, it might seem that the use of batteries is fairly cheap. And yes, batteries are cheap, but replacing them is not. Changing a battery in a sensor also involves costs for labor access, replacing, testing, documentation, and service margin, which need to be calculated as well. Typical battery service cost is between $26 per sensor if all system batteries are replaced and $275 if a single battery must be replaced. One-time battery replacement of 10,000 sensors keeps one installer busy for one year full-time.

On top of that, batteries cause environmental harm and create a safety risk. They contain many harmful substances (zinc, nickel, lithium, cobalt) and increase the risk of fire or explosion – not something anybody would want in an office environment or actually anywhere.

Battery-free and wireless sensors offer a cost-effective, sustainable, and future-proof way to set up an IoT solution in any office building. They use movement, light, or temperature differences as a power source based on the principle of energy harvesting. This makes them work completely maintenance-free. Another bonus is that they can be flexibly installed anywhere in the room; they can be put on walls, ceilings, desks, windows, or even moving parts. That’s why they are also ideally suited for retrofits.

See also: Redefining Smart Buildings: Focus on the People

Why desk-sharing is the IoT killer application

Desk-sharing models offer incredible monetary and ecological benefits as companies can save typically 25% of space and desks. Extrapolated, this means that companies with 100,000 employees can save over $200 million/year.

Wireless and battery-free vibration sensors are ideally suited for this type of application. Attached to desks, they detect which workstations are occupied or still free to work on. It is important to choose sensors that work reliably and secure privacy in order to ensure system performance and user acceptance. An integrated Near Field Communication (NFC) interface allows employees to easily check in and out of the desk booking system or app using their mobile phone. If there is no desk booking required or personal check in is not done, 100% privacy is given, and the booking app still works using the real-time desk occupancy data given by the sensors – free desks and real utilization rates are still provided. Desks that are not part of this desk-sharing model obviously don‘t need to be equipped with sensors. A plus: the desk utilization sensor also signals the need for cleaning, and the cleaning staff can confirm their work by using the NFC interfaces on their phones. In that way, clean desks and work areas are always provided. This is also an important aspect in terms of keeping the infection rates with COVID-19 as low as possible and creating a safe and comfortable working environment.

Good air quality in offices is a must

Another measure to provide a healthy working environment and to protect employees from COVID-19 is always ensuring great air quality. We know that the amount of CO2 in the air is an indicator of the possible virus load, and that’s why measuring air quality is a necessity in order to get the pandemic under control. Adding CO2 sensors helps companies with 100,000 employees to save over $13 million/year if you assume a healthy environment will lead to one less sick day per employee on average. At the same time, motivation and productivity increase by up to 50% (see numbers above).

Less CO2 emissions thanks to IoT sensors

Installing a smart building automation system has positive effects on the CO2 emissions of a building. This is important because buildings cause around 40% of worldwide CO2 emissions, 98.5% of these are existing buildings. The actual energy requirement is detected by sensors – especially local temperature, presence, and window status (open/closed). The local actuators are then controlled as required, either directly or via a building automation system. With such a solution, energy savings of up to 30% are possible. Based on these facts, you can easily predict that IoT-based HVAC solutions will become mandatory for CO2 reduction. Compared to replacing the entire existing building envelope, which would have an ROI of up to 60 years, the digitalization of the building has a much more reasonable ROI of only around four years. Cost savings for a company with 100,000 employees would be up to $2.75 million/year. With rising energy costs, this will even be a lot more in the future.

All in all, IoT solutions play a crucial part in not only creating better workplaces and optimizing the energy consumption of buildings but also in significantly reducing yearly operating costs. Sensors that are wireless and battery-free come with significant advantages like network flexibility, sustainability, and maintenance-free operation. This is really something every company should consider nowadays when choosing sensors for their IoT solution.

Armin Anders

About Armin Anders

Armin Anders is VP Business Development and Co-Founder of EnOcean. After graduating in electrical engineering – with a focus on information and communication technology – at Karlsruhe University, Armin Anders spent a number of years as marketing manager for microcontrollers at Siemens AG. He then worked as a project manager for Siemens Corporate Technology, spent an interim period as assistant to the central executive, and then joined Siemens Technology Accelerator GmbH as a venture manager responsible for startups. Armin Anders is one of the five EnOcean founders and drew up the business plan for the company.

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