Residential heating, ventilation, and air conditioning (HVAC) systems constitute a significant proportion of energy usage in buildings, necessitating energy management optimization. In this context, occupancy-aware HVAC control is a promising option with 20–50% energy savings in homes. However, occupancy sensing technology suffers from long payback times, privacy issues, and poor comfort. Moreover, there is an increasing need for further advanced technologies that help regulate indoor air quality in addition to energy control.

To meet these expectations, scientists have recently turned to intelligent control methods such as quantum reinforcement learning (QRL)-based on quantum computing principles. Such approaches can notably accelerate the machine learning process as well as handle the complexity of real-world building dynamics.

In a new study, a group of researchers from the Republic of Korea, led by Sangkeum Lee, Assistant Professor of Computer Engineering at Hanbat National University, have presented the first demonstration of continuous-variable, quantum-enhanced reinforcement learning for residential HVAC and home power management. Their findings are published in the journal Energy and AI.

Dr. Lee says, “Unlike conventional reinforcement learning techniques, QRL leverages quantum computing principles to efficiently handle high dimensional state and action spaces, enabling more precise HVAC control in multi-zone residential buildings. Our framework integrates real-time occupancy detection using deep learning with operational data, including power consumption patterns, air conditioner control data, and external temperature variations.”

Furthermore, the proposed technology integrates features such as multi-zone cooling—to control the temperature of individual zones in a building—and clustering—to group similar data points and adjust cooling. In this way, a single controller jointly optimizes comfort, energy cost, and carbon signals in real time.

The researchers performed simulations based on real world data from 26 residential households over a three-month period. They found that QRL HVAC control significantly outperforms deep deterministic policy gradient method as well as proximal policy optimization algorithm, while maintaining thermal comfort, achieving 63% and 62.4% reductions in power consumption, respectively, and 64.4% and 62.5% decrease in electricity costs, respectively.

The present approach comes with many more benefits. It is retrofit-friendly and works with standard temperature, occupancy, and CO₂ sensors and common HVAC equipment and thermostats. It is also robust to uncertainty, easily handling noisy forecasts on weather and occupancy and device constraints. In addition, it has a generalizable framework that can be extended from apartments to small buildings and microgrids.

Dr. Lee says, “It can be utilized in smart thermostats and autonomous home energy management systems that co-optimize comfort, bills, and emissions without manual tuning and rooftop photovoltaics and home battery scheduling. Our framework is also useful for utility demand-response and time-of-use programs with automated control.”

QRL-based HVAC control can notably be applied at community or campus scale through grid-interactive efficient buildings and virtual power plants (VPPs). Herein, millions of homes can coordinate as VPPs to stabilize renewables-heavy grids. It can also ensure personalized indoor environmental quality within carbon budgets and integrate advanced intelligent control options.

As hardware matures in the coming years, quantum-accelerated policy research could facilitate faster training for complex multi-energy systems such as HVAC, electric vehicles, and energy storage systems. In the long term, this work is expected to guide the path toward standardized secure controllers that can be certified and deployed at a wide scale.

Provided by
Hanbat National University Industry–University Cooperation Foundation

Concrete already builds our world, and now it’s one step closer to powering it, too. Made by combining cement, water, ultra-fine carbon black (with nanoscale particles), and electrolytes, electron-conducting carbon concrete (ec³, pronounced “e-c-cubed”) creates a conductive “nanonetwork” inside concrete that could enable everyday structures like walls, sidewalks, and bridges to store and release electrical energy. In other words, the concrete around us could one day double as giant “batteries.”

As MIT researchers report in a new PNAS paper, optimized electrolytes and manufacturing processes have increased the energy storage capacity of the latest ec³ supercapacitors by an order of magnitude.

In 2023, storing enough energy to meet the daily needs of the average home would have required about 45 cubic meters of ec³, roughly the amount of concrete used in a typical basement. Now, with the improved electrolyte, that same task can be achieved with about 5 cubic meters, the volume of a typical basement wall.

“A key to the sustainability of concrete is the development of ‘multifunctional concrete,’ which integrates functionalities like this energy storage, self-healing, and carbon sequestration. Concrete is already the world’s most-used construction material, so why not take advantage of that scale to create other benefits?” asks Admir Masic, lead author of the new study, MIT Electron-Conducting Carbon-Cement-Based Materials Hub (EC³ Hub) co-director, and associate professor of civil and environmental engineering (CEE) at MIT.

The improved energy density was made possible by a deeper understanding of how the nanocarbon black network inside ec³ functions and interacts with electrolytes.

Using focused ion beams for the sequential removal of thin layers of the ec³ material, followed by high-resolution imaging of each slice with a scanning electron microscope (a technique called FIB-SEM tomography), the team across the EC³ Hub and MIT Concrete Sustainability Hub was able to reconstruct the conductive nanonetwork at the highest resolution yet. This approach allowed the team to discover that the network is essentially a fractal-like “web” that surrounds ec³ pores, which is what allows the electrolyte to infiltrate and for current to flow through the system.

“Understanding how these materials ‘assemble’ themselves at the nanoscale is key to achieving these new functionalities,” adds Masic.

Equipped with their new understanding of the nanonetwork, the team experimented with different electrolytes and their concentrations to see how they impacted energy storage density.

As Damian Stefaniuk, first author and EC³ Hub research scientist, highlights, “we found that there is a wide range of electrolytes that could be viable candidates for ec³. This even includes seawater, which could make this a good material for use in coastal and marine applications, perhaps as support structures for offshore wind farms.”

At the same time, the team streamlined the way they added electrolytes to the mix. Rather than curing ec³ electrodes and then soaking them in electrolyte, they added the electrolyte directly into the mixing water. Since electrolyte penetration was no longer a limitation, the team could cast thicker electrodes that stored more energy.

The team achieved the greatest performance when they switched to organic electrolytes, especially those that combined quaternary ammonium salts—found in everyday products like disinfectants—with acetonitrile, a clear, conductive liquid often used in industry. A cubic meter of this version of ec³—about the size of a refrigerator—can store over 2 kilowatt-hours of energy. That’s about enough to power an actual refrigerator for a day.

While batteries maintain a higher energy density, ec³ can in principle be incorporated directly into a wide range of architectural elements—from slabs and walls to domes and vaults—and last as long as the structure itself.

“The Ancient Romans made great advances in concrete construction. Massive structures like the Pantheon stand to this day without reinforcement. If we keep up their spirit of combining material science with architectural vision, we could be at the brink of a new architectural revolution with multifunctional concretes like ec³,” proposes Masic.

Taking inspiration from Roman architecture, the team built a miniature ec³ arch to show how structural form and energy storage can work together. Operating at 9 volts, the arch supported its own weight and additional load while powering an LED light.

However, something unique happened when the load on the arch increased: the light flickered. This is likely due to the way stress impacts electrical contacts or the distribution of charges.

“There may be a kind of self-monitoring capacity here. If we think of an ec³ arch at an architectural scale, its output may fluctuate when it’s impacted by a stressor like high winds. We may be able to use this as a signal of when and to what extent a structure is stressed, or monitor its overall health in real time,” envisions Masic.

The latest developments in ec³ technology bring it a step closer to real-world scalability. It’s already been used to heat sidewalk slabs in Sapporo, Japan, due to its thermally conductive properties, representing a potential alternative to salting.

“With these higher energy densities and demonstrated value across a broader application space, we now have a powerful and flexible tool that can help us address a wide range of persistent energy challenges,” explains Stefaniuk.

“One of our biggest motivations was to help enable the renewable energy transition. Solar power, for example, has come a long way in terms of efficiency. However, it can only generate power when there’s enough sunlight. So, the question becomes: How do you meet your energy needs at night, or on cloudy days?”

Franz-Josef Ulm, EC³ Hub co-director and CEE professor, continues, “The answer is that you need a way to store and release energy. This has usually meant a battery, which often relies on scarce or harmful materials. We believe that ec³ is a viable substitute, letting our buildings and infrastructure meet our energy storage needs.”

The team is working toward applications like parking spaces and roads that could charge electric vehicles, as well as homes that can operate fully off the grid.

“What excites us most is that we’ve taken a material as ancient as concrete and shown that it can do something entirely new,” says James Weaver, a co-author on the paper who is an associate professor of design technology and materials science and engineering at Cornell University, as well as a former EC³ Hub researcher.

“By combining modern nanoscience with an ancient building block of civilization, we’re opening a door to infrastructure that doesn’t just support our lives, it powers them.”

This story is republished courtesy of MIT News (web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and teaching.

More USB-C Cables We Have Tested

There are so many cables out there, and plenty of solid options did not make the cut. Here are a few I’ve tested and liked.

Twelve South PowerCord for $30: While I don’t think we want to go back to permanently attached cables and power adapters, they offer a simplicity that could be useful for some folks or situations. The PowerCord from Twelve South is thick and durable-feeling, with a tangle-resistant woven (4- or 10-foot) USB-C cable attached to a compact 30-watt (Power Delivery) wall plug.

EcoFlow Rapid Pro for $21: Kept out of a place above by Anker’s cables, this durable charging cable from EcoFlow is a solid choice if you want fast charging, since it can supply 240 watts. It also has tough metal ends, a lovely woven finish, and comes with a cable tie.

Nomad Chargekey for $29 and USB-C Cable for $25: The Chargekey is a handy wee addition to your keyring with 12 cm of braided cable capable of delivering 240 watts and up to 10 Gbps data transfer, though it can be a little awkward to use. I also tried Nomad’s new Kevlar-reinforced USB-C cable, which is also 240 W but only has 480 Mbps data transfer. It feels durable with metal ends and braided cable, but you can get more capable cables for less.

QDOS PowerMotion Ultra for £40: This USB 4.0 cable is a solid alternative to our top picks for folks in the UK, combining up to 240-watt charging with data transfer speeds up to 40 Gbps. It is relatively thick, feels durable, and comes with a lifetime warranty. I like the braided nylon finish and color-matched cable tie. I also tried the QDOS Powerloop (£20), a handy wearable charging cable that doubles as a lanyard strap. It’s thick, woven, and durable, with screw-off ends that reveal a USB-C cable capable of supplying 60 watts of power and 480 Mbps of data.

Chargeasap Connect Pro for $60: Magnetic tip cables can be handy for kids and folks with dexterity issues. The idea is you stick the relevant tip in your device and then attach the cable magnetically when you need to charge. This one also has an LED display to show real-time power usage. It works best if you leave the tips in your devices, but that means they can’t be charged by regular cables, and the tips are very easy to lose if you remove them. Performance-wise, it’s a standard 100-watt charging cable.

Krafted Connex for £30: I like the idea of a Swiss Army Knife–style charging cable keyring, but the execution here is flawed. It does offer USB-A, USB-C, Lightning, and MicroUSB, but the flip-out plugs don’t have any cable attached, so they are not very adjustable, making it tough to plug into some ports. The Rolling Square InCharge X 6-in-1 Cable above is the same price and works far better.

Scosche Strikeline Premium USB-C Cable for $25: This braided cable comes in various lengths all the way up to the 10-foot cable I tested, and it’s a good alternative to our best long cable above if data transfer is more important to you than charging speed because it offers 5 Gbps data speeds, but only 60 watts for charging.

Ugreen Uno USB-C Cable for $10: I love the smiley-faced Uno line from UGreen, but I assumed the display on this cable would show the charging rate. It does not. It just displays smiley eyes when charging and changes when fully charged. I tested the 6.6-foot cable, but it also comes in 1.6-, 3.3-, or 10-foot lengths. It feels durable and is reasonably priced, but it is rated at a very ordinary 100 watts and 480 Mbps.

Native Union Pocket Cable for $30: This wee braided USB-C to USB-C cable is perfect for slipping on a keyring to ensure you are never caught without a cable. It’s a nice design with braided cables, but you only get around 7 inches, and it maxes out at 60 watts. It is built to last from recycled materials, USB-IF certified, and comes with a lifetime warranty.

Caudabe ChargeFlex for $25: This was our Lightning recommendation, and it’s still good, but the price has gone up and there’s no need to spend this much. It is a thick braided cable reinforced with Kevlar for durability. There is a leather clip you can use for cable management, and the ridged finish on the connectors makes them easy to grip when unplugging.

Cable Matters Gen 2 USB-A to USB-C cable for $10: This is a good alternative to our pick above if you want faster data transfer speeds (it maxes out at 10 Gbps), but it is limited to 15 watts for charging.

Bluebonnet Eco-Friendly Charging Cable for $25: Bluebonnet (an Austin-based studio named after the Texas state flower) made this cable from naturally biodegradable wheat straw. It promises 50,000 plus bends and uses plastic-free packaging. I love the dappled blue finish and the cream ends. They make it easy to pick this cable out of the crowd. It’s nothing special performance-wise, offering up to 60-watt charging and 480 Mbps data transfer.

RUGD Rhino Power USB-C to USB-C for £11: This is a solid option for folks in the UK seeking a tough cable. It has a braided nylon finish and can withstand a minimum of 100 kilograms of tension and 100,000 bends. It can also deliver up to 60 watts.

Casetify Powerthru USB-C to Lightning Cable for $25: This tough, braided cable comes in some fun colors (most notably cotton candy), but it’s kinda pricey for a 100-watt charging cable.

Iniu Braided USB-C Cable for $6: This is a cheap, 6.6-foot USB-C to USB-C charging cable that tops out at 100 watts. Data transfer is only 480 Mbps. One end lights up green when it’s charging.

Lindy USB 3.2 Type C to C Cable for $23: These active cables are suitable for hooking monitors up to your computer, and they support up to 8K at 60 Hz and 4K at 120 Hz. They also support DisplayPort 1.4. I tested the longer 3- and 5-meter variants that max out at 60 watts for Power Delivery and 10 Gbps for data (but they’re out of stock). The shorter cable linked here can go up to 20 Gbps. They work well and feel durable, but they’re a bit pricey.

Satechi USB-C to USB-C Charging Cable for $20: Gear from Satechi always has a classy look, and its braided nylon cables are no exception. This one is 6.5 feet, has a Velcro strap, and is capable of 100-watt charging, with support for PD and QC. Sadly, data transfer is limited to 480 Mbps.

Plugable Thunderbolt 4 Transfer Cable for $70: This active Thunderbolt 4 USB-C to USB-C cable matches our top pick with support for 100-watt charging and data transfers up to 40 Gbps. It is 6.6 feet long and comes with a two-year warranty.

Belkin Boost Charge USB-C for $10: This cable maxes out at 12 watts and 480 Mbps. The basic PVC finish is the cheapest, but you can opt for braided nylon too; both come in black or white at 3.3 or 6.6 feet. These cables are USB-IF certified and work as advertised (I’ve been using one in the car for the last few months).

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