Thin And Highly Insulating Walls Lower Heating Costs

Better thermal insulation means lower heating costs – but this should not be at the expense of exciting architecture. A new type of brick filled with aerogel could make thin and highly insulating walls possible in the future – without any additional insulation layer.

The calculation is simple: the better a building is insulated, the less heat is lost in winter – and the less energy is needed to achieve a comfortable room temperature. No wonder, then, that the Swiss Federal Office of Energy (SFOE) regularly raises the requirements for building insulation.

In order to achieve the same insulation values as a 165 mm thick wall of aerobricks, a wall of perlite bricks must be 263 mm thick – and a wall of non-insulating bricks even more than one meter!

Traditionally, the insulating layers are applied to the finished walls. Increasingly, however, self-insulating bricks are being used – saving both work steps and costs and opening up new architectural possibilities. Insulating bricks offer a workable compromise between mechanical and thermal properties and are also suited for multi-storey buildings. They are already available on the market in numerous models: some have multiple air-filled chambers, others have larger cavities filled with insulating materials such as pearlite, mineral wool or polystyrene. Their thermal conductivity values differ depending on the structure and filling material. In order to reach the insulation values of walls with seperate insulating layers, the insulating bricks are usually considerably thicker than normal bricks.

Empa researchers have now replaced Perlite in insulating bricks with Aerogel: a highly porous solid with very high thermal insulation properties that can withstand temperatures of up to 300°C (see box). It is not a novel material for the researchers: they have already used it to develop a high-performance insulating plaster which, among other things, allows historical buildings to be renovated energetically without affecting their appearance.

Together with his colleagues, Empa researcher Jannis Wernery from the research department «Building Energy Materials and Components» has developed a paste-like mixture of aerogel particles to be used as filler material for the brick. «The material can easily be filled into the cavities and then joins with the clay of the bricks», says Wernery. «The aerogel stays in the bricks – you can work with them as usual.» The «Aerobrick» was born.


Nanoparticles Activated By Solar Energy Boil Water

Young researchers created a superconducting heat ink that functions as a solar heater. It heats water up to 68 degrees Celsius and is 40 percent cheaper than commercial inks.

hot shower 2

A pipe exposed to the sun reaches a temperature of 40 C°, if we add the superconducting ink the temperature increases 70 percent and reaches 68 C°,” says Sandra Casillas Bolaños, master at the Technological Institute of the Lagoon (ITL), in north of Mexico, and head of the project.

She explains that the ink acts as a boiler that contains nanoparticles activated by solar energy and increasing the temperature.


The ink is made of two layers, the first is an internal magnetic titanium nanoparticle, which is responsible for trapping the heat and the second is external and consists of a coating of tungsten (filament in light bulbs) which researchers transform into a nano salt and adhere with polyvinyl alcohol, to finish with a layer of copper.

Casillas Bolaños states that by a treatment called burnishing copper blackens in order that trap and retain heat inside the particles. “Thus the center is heated more intensely: first the titanium, then tungsten and finally the copper“.

The project has been developed for two years and the product is classified as an ink because it uses a series of solvents making it fast drying and with an odor similar to hair dye. The ink is applied on the surface of a conventional pipe that carries water and to potentiate the heat, students working on the project with professor Casillas Bolaños in the nonmetallic materials field, put two layers of PET bottles over the tubes in order to create a greenhouse effect and raise the temperature faster, as well as protect the ink from outdoor wear.

The technology has been implemented in some houses, where, by flowing for five meters water at 68 C° is obtained instantly, and even in cloudy weather the ink nicely captures the heat. Sandra Casillas adds that the ink was implemented in a major sports complex of the city to heat the pool, where two million cubic meters of water are heated from 26 to 37 C°. To achieve this, the researcher and her team placed tubes covered with ink on the edge of the indoor pool and a pump pulls the liquid from seven o’clock until the sun sets. As it flows, the water is heated and reaches the ideal temperature.

The ink is in the process of patenting and is intended to be market at 600 pesos a liter (about 40 dollars); however, for house piping only 150 pesos (10 dollars) are invested because very little is needed, says Casillas Bolaños.


Smart Clothes Maintain The Confortable Temperature

Imagine a fabric that will keep your body at a comfortable temperature—regardless of how hot or cold it actually is. That’s the goal of an engineering project at the University of California, San Diego, funded with a $2.6M grant from the U.S. Department of Energy’s Advanced Research Projects Agency – Energy (ARPA-E). Wearing this smart fabric could potentially reduce heating and air conditioning bills for buildings and homes.

The project, named ATTACH (Adaptive Textiles Technology with Active Cooling and Heating), is led by Joseph Wang, distinguished professor of nanoengineering at UC San Diego.

By regulating the temperature around an individual person, rather than a large room, the smart fabric could potentially cut the energy use of buildings and homes by at least 15 percent, Wang noted.

T-shirt with printed electrodes

Garment-based printable electrodes developed in the lab of Joseph Wang, distinguished professor of nanoengineering at UC San Diego, and lead principal investigator of ATTACH

In cases where there are only one or two people in a large room, it’s not cost-effective to heat or cool the entire room,” said Wang. “If you can do it locally, like you can in a car by heating just the car seat instead of the entire car, then you can save a lot of energy.”

93° F (33,9° Celsius) is the average comfortable skin temperature for most people,” added Renkun Chen, assistant professor of mechanical and aerospace engineering at UC San Diego, and one of the collaborators on this project.

Chen’s contribution to ATTACH is to develop supplemental heating and cooling devices, called thermoelectrics, that are printable and will be incorporated into specific spots of the smart fabric. The thermoelectrics will regulate the temperature on “hot spots”—such as areas on the back and underneath the feet—that tend to get hotter than other parts of the body when a person is active.

This is like a personalized air-conditioner and heater,” said Chen. “With the smart fabric, you won’t need to heat the room as much in the winter, and you won’t need to cool the room down as much in the summer. That means less energy is consumed. Plus, you will still feel comfortable within a wider temperature range,” he added.

The researchers are also designing the smart fabric to power itself.