When it´s possible to build an airplane out of hemp, it should also be possible to build houses made of hemp. Or more precisely; hempcrete. Hemp grows fast and therefore binds a lot of co2 in short amounts of time. Because the production of hempcrete is producing less CO2 than the hemp in hempcrete has been absorbing, its overall carbon footprint is negative. Hempcrete has extraordinary insulating properties, prevents moisture (and mold), is flame-resistant and sound-absorbing. It is strong enough to build single-storey buildings with it. For higher buildings stronger components (for example wood) are necessary. Timber is currently CO2 neutral or is slightly producing more CO2 than it stores (due to transport and processing).
When we build with timber for strength in combination with hempcrete to fill the gaps in between (and actually building the walls), the process of building a house can still store more CO2 than it produces. But even in combination with steel or concrete hempcrete can substantially ameliorate carbon footprint. Fun fact: Because it is weaker than concrete and deforms under stress, in case of an earthquake it can prevent a building from collapse. Because insead of crumbling up like a house of card (each "card" staying intact) as it might be the case with concrete walls, walls made of hempcrete tend to deform instead of falling one on another.
Heat Pumps (also see this post) are usually used to heat single houses. But a heater can also be centralized and heat a whole city district or a whole city. The heater in that case is basically a supersized heater that is connected to some or all the buildings of a certain area. The heater will warm up water to 50°C - 130°C. Thanks to many miles long insulated pipes, the heated water then flows to all the houses connected.
The company Everllence built a massive heat pump that - instead of using the warm subsoil as it is often the case with heat pumps for single buildings - uses the warmth of seawater. Because similar to soil, seawater in winter is warmer than the air. (8-10°C). Making the heat pump much more effective. The main advantage of such a centralized district heater are that the supplied buildings save a lot of space as each house doesn´t need its own heater and like this many buildings can use the warmth from the sea even if they are far from it. The company STRABAG will build a similar heat pump by using the warmth of a river.
The image on the right shows nanocellulose aerogel that has outstanding passive cooling features. It was invented by Chinese scientists from Nanjing Forestry University. The principle of radiative cooling is gaining importance for the transition towards a sustainable net zero world. As already explained in another post on this website (scientists who are using this principle to generate power), with the help of radiative cooling we can basically send heat out of earth´s atmosphere into outer space. This happens when thermal radiation occurs within a specific range of wavelength (8–13 μm) which is also called the "atmospheric window". Within that wavelength range it is likely that the radiation won´t get absorbed by earth´s atmosphere and therefore leave into space. There are several companies applying or producing different kinds of materials that use this efect. What Chenyang Cai (E-Mail) and his colleagues managed to do is to create a material that not only has ideal radiative cooling properties but is also eco-friendly and stays clean (dust would lower its effectiveness). The nanocellulose aerogel film properties are so amazing that they can reduce indoor temperature of a house in summertime and under direct sun exposure by 6.9° Celsius.
Moroccan startup Eco-dôme is building houses in an ancient traditional way. Because as it turns out, the traditionally built houses made from soil are not only cheaper and more ecological to build but have also a natural cooling effect in summer and a warming effect in winter. Which means that most of the time no additional energy is needed to cool or heat the interior. Eco-dôme developped new economical building techniques and is adding contemporary materials to catapult this genius but forgotten way of house building into the 21st century. In the past, building houses made of soil used to be common a bit everywhere around the globe. There are different techniques that are currently being rediscovered and improved.
Wood from sustainable forests is one of or the best construction materials in terms of sustainability. Trees are turning CO2 from the air into wood and oxygen. So wood is basically CO2 that has been filtered out of the atmosphere. When we are building with wood, we are keeping the harmful CO2 out of the atmosphere and therefore tackling global warming. For these reasons in Stockholm, Sweden a whole district (sickla) is currently being built with wood as its main component. 70% of Sweden´s surface is forested and every cut tree must be replaced by law. Making it the ideal country for such a project. Architects around the world are also focussing on new techniques to be able to built wooden skyscrapers. There is even a new term: Plyscraper. High-rise buildings have the advantage that less ground surface is needed so there is more land for nature or agriculture.
Depending on where we live our houses are a main cause of CO2 emissions. Depending on where we live because it makes a huge difference whether we live in some place where it's around 20 degrees Celsius all year round or in a place with hard and long winters. Because heating a house needs a lot of energy. Switzerland is a place where it is rather cold during winter so if we find a way to build a house with 0 emissions in Switzerland it should be possible in most if not all other parts of the world too.
In the image here you see the world's first apartment building (with 9 family apartments) that is producing all the energy its residents need. So no connection to any energy grid is needed. No oil has to be delivered. No gas. No connection to the electrical grid. Cooking or heating in winter, hot shower. All the energy comes from the house itself.
The facade and the roof is completely covered in solar pannels. And during the summer when the sun is shining the most, the excess electricity will be used to produce hydrogen and fill up tanks in the basement that will heat the building in winter. In fact, this concept worked so well that the house is producing more energy than it needs which is why in 2019 they decided to actually do connect it to the grid. Not to receive electricity. But to give. Immagine if all houses were built like this. This was a project of the Umwelt Arena Switzerland. More houses like this were built or are currently in construction because it was a full success.
To achieve the goal of a 0 emission house like in the post above or to at least dramatically lower its carbon emissions (in a place with cold winters) there are different technologies available. The most common one are solar panels. You can also add smaller sized windwheels that don't stick out too much so they won't disturb your neighbours. But because heating in cold winters is extremely energy-intensive, additional technologies are required. Heating with wood can be a CO2-neutral technology as well. By wood I mean either burning wood at a fireplace or masonry heater (there are fireplaces that are specifically meant for heating with a glass door to avoid smoke in your rooms). Or pellets, which is a modern way of heating with wood. But heating with wood is only environmentally friendly as long the wood that is being burned comes from sustainable forests which means each cut tree has to be replaced by a new one. If everybody that is currently heating with oil or gaz would switch to wood we wouldn't have enough sustainable forests in the world to cover the demand so wood can not be the only solution. That's why other new technologies are indispensable.
Heat Pumps are one of those new technologies. They work with electricity and are "pumping" the heat either from the air outside or from the ground into the building. They work with the same principle as refrigerators but the other way round. Fun fact: Even with freezing temperatures outside, the air still contains "heat". Because heat is basically energy and as long air temperature is above absolute zero (-273°Celsius) the air still contains energy. The heat pump just has to "pump" more and therefore needs more electricity than on warmer days. Since the ground is usually warmer than the air in winter, many house owners decide to use the heat from the ground by digging holes deep under the surface. In their frontyard for example. Pipes filled with water will then lead the heat from underground into the actual heat pump in the house. Because a heat pump doesn`t produce heat by itself but instead "filters out" the already exisitng heat (that already contains the energy), with 1 MWh the heating pump can "pump" heat into the house that is worth up to 4MWh. That´s why this technology is so genius and is actually making sense.
Producing concrete affords a lot of energy and therefore is responsible for 8% of the worlds total CO2 emissions. In Switzerland the rubble of demolished concrete constructions are being recycled. 50% of it is being used for new buildings and the rest for roadmaking. The Swiss company Neustark now has invented a procedure to reduce concretes CO2 footprint by catching the emitted CO2 from biogas plants and enrich the concrete rubble with it. In a chemical reaction the CO2 will become part of the newly mixed concrete. Tests have shown that concrete enriched with CO2 is even more robust than ordinary concrete. Allowing to reduce the CO2 footprint of buildings made of concrete even more. As less material is needed for the same amount of stability.
When (concentrated) sodium hydroxide (lye) is mixed with water, a chemical reaction happens that produces heat. Swiss researchers used this effect and created a sodium hydroxide lye - battery to store excess energy from summer to use it in winter. During winter when heat is needed, the above described reaction is taking place.
During summertime, when solar pannels are producing more energy than required, this chemical reaction can be reversed. Heat from the solar pannels will separate water again (the sodium hydroxide solution gets more concentrated again). The big advantage compared to lithium batteries for example is that the concentrated lye could in theory be stored forever without losing any energy over time. All that is needed is is a bit of space to store the liquids.
The elaborated system needs the water to be vaporized before it reacts with the sodium hydroxide. For that reason they use reduced pressure in one pipe So the water can evaporate at around 10°Celsius already. The steam then goes into the second pipe where the sodium hydroxide reacts with the water m0lecules, producing heat to around 50°C which is enough heat for a modern underfloor heating.