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As we look forward to the question of how we will heat our homes in the future, it is important to acknowledge the plethora of technological innovations on the horizon with the capacity to change the nature of our answer. Since 2014, ARPA-e has funded a number of projects under its ‘Delivering Efficient Local Thermal Amenities’ (DELTA) program. The projects in this program aimed to develop novel solutions focused on providing thermal comfort to the person individually rather than to an entire room with the purpose of providing thermal comfort to everybody within it. A little over 4 years since these projects received funding, we have opted to assess how some of these technologies have progressed, and what they could mean for the future of personal heating.

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The State University of New York (SUNY) at Stony

Brook: Electroactive Smart Air-Conditioner Vent

Registers (eSAVER)for Improved Personal Comfort

and Reduced Electricity Consumption

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This project was awarded $1.36 million in funding back in

2015, and was concluded in July of 2018, with the project’s

final report available here. The basic idea of the project was

to develop a system that utilised high-speed air curtains

around an individual with low-speed airflow within to create a

micro-environment in which to cool/heat the individual. This is

achieved by retrofitting nozzles of different sizes and shapes

to existing units that would achieve the desired effect. When

compared to the conventional method of cooling/heating a

room, the system could be expected to reduce overall

heating/cooling energy needs by up to 30%, could be

tailored to the specific thermal needs of each occupant,

and could even move the airflow in correspondence with

the movements of the occupant.

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The design of the system was tested and enhanced throughout the course of the research, and Computational Fluid Dynamic simulations were developed to demonstrate the designs efficiency, both to apparent success. SUNY acknowledge in their report that a complete prototype had still not been

developed at the point of publishing, and that one obstacle yet to be overcome would be to optimise the device based on the size of its occupant. However, the results so far appear to be optimistic, and with the potential rise of integrating smart technologies into our buildings, it does not seem unrealistic to believe that this sort of solution could find its way into our offices sometime soon.

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Cornell University: Thermoregulatory Clothing System for Building Energy Saving

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This project for a Thermoregulatory Clothing System was granted almost $3 million dollars in funding and the summary of their work can be found here. This system takes a different approach to that of the eSAVER, providing direct thermal comfort through clothing rather than near-range energy transfer. They argue that this approach is less complex and potentially less expensive. Thermoregulatory clothing already exists in many forms; for example, spacesuits or heat-reflective clothing for firefighters. However, these are generally tailored for specific extreme needs and can generally only be used to either conserve or reduce heat. The aim of this project was to develop a 'portable thermoelectric energy unit that can provide both cooling and heating for personal thermal management’, with the eventual goal of expanding the range of thermal comfort by 2.2C. By expanding the thermal comfort range by this amount, it is argued, energy costs related to heating/cooling could be reduced by up to 15%. A focus of the project was to produce a heat sink

that could be integrated into an item of clothing, meeting pre-determined targets for weight and

size.

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Throughout the project, the group of researchers developed a prototype

of the system, which minimised the size of the heat sink, and provided

heated/cooled air through a ‘tree-like rubber tube network’ integrated into

the clothing’s fabric. Whether the system is in heating or cooling mode is

simply determined by the direction of the current in the device, and so can

easily be switched from one mode to the other when needed. All of the

products used in the device are available off-the-shelf which could lead to

decreased costs if it did come to mass production, and the efficiency of

the prototype could certainly be improved if better components became

available for integration in the future. Looking at the design in its current

form it seems unlikely that we will see this product on our shelves in the

very immediate future, but as an idea, this sort of system seems to stand

strong and could have the potential to change the way we view heat in

years to come if this work is continued. Much like with the integration of

smart technology into our homes, wearable technology is becoming

increasingly common, and personal thermoregulatory systems could

easily become another example of that.

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Otherlab: Passive Thermo-Adaptive Textiles with Laminated Polymer Bimorphs

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Unlike the previous two projects, this project from Otherlab is still active, and is due to be completed in May 2019. The project has received over $5.4 million in funding, and was initially only due to run for 2 years but was awarded further funding to conduct a second phase of research. Due to the fact that the project is as yet incomplete, there is no fully comprehensive report on the findings of the project, but a blog post from a member of the team involved and an innovation update from May of last year give a pretty good idea of what Otherlab have been up to.

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The basic principle approaches the problem from yet

another direction; much like the team at Cornell, Otherlab

aimed to solve the issue of personal comfort through smart

clothing, but what makes their idea different is that the end

product would be completely passive. Through utilising the

different ways in which materials respond to heat, Otherlab’s

goal was to produce a wearable garment that would wear

like any other garment at normal temperatures, but could

expand, producing air pockets and, thus, insulation, in

response to colder temperatures, all without any need for

computation of human intervention. Much of their work in the

first phase of their research was about trial and error,

failure and repetition, as is admitted (and described in

brilliant detail) on the blog mentioned above. However,

Rome wasn’t built in a day, and the progress that they have

made since 2015 is genuinely impressive. The resultant

textile automatically doubles its insulation properties from

27C to 17C, potentially allowing for thermal comfort whilst

wearing the textile between these two temperatures. The

second phase of research is largely focused on ensuring

‘production reliability and performance characteristics’ with

the very real prospect of this product being released onto

the market in the very near future.

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Of all the exceptional ideas funded in ARPA-e’s DELTA program, this one in particular stands out. Not only does the theoretical final product seem least complex and most ‘smart’ (given its passivity), but it approaches the problem from an entirely new angle, looking to develop a completely new technology in response to the problem, with the same goal of expanding the thermal comfort range and reducing the energy need in regards to heating. The idea of wearing an item of clothing that in its very nature responds to the climate it is in is truly innovative, and something which one can easily imagine becoming extremely popular in years to come. Moreover, at a glance it seems that the potential uses of this technology could be wide-ranging, potentially being used in other products such as curtains or bedding. It is therefore no surprise that the team at Otherlab have gained the attention of private investors keen to start a spin-off company specifically related to this product. It will be very exciting to see a comprehensive review of their work when it is published later this year, and it seems very likely that it won’t be the last we see of this technology in years to come.