3D printing for passive buildings
3D printing of buildings, which has advantages in terms of cost and speed of construction, can also facilitate the design of near zero energy buildings.
As specified in the Directive 2012/27/EU, buildings represent 40% of European Union’s final energy consumption and are crucial to achieving the EU’s objective of reducing greenhouse gas emissions by 80-95% by 2050 compared to 1990 (1). The European Commission promotes energy efficiency in buildings through the energy performance building directive (EPBD recast) where the concept of nearly zero energy building (NZEB) has been introduced as a minimum energy performance level to be reached.
In this context, 3D printing of buildings appears to be a promising option. Not only focused on energy performance, 3D printing is at the same time a very efficient process.
. In April 2017, PassivDom, a Ukrainian company, unveiled a prototype passive house built using 3D printing technology. This house has a surface of 36 m2, features a 3D printed carbon-reinforced fiberglass frame and numerous glazing. It has vacuum panel insulation and, according to the designers, it meets the Passivhaus standard (2).
. In July 2020, the first 3D-printed house in the Czech Republic was completed in České Budějovice. Developed by building company Stavební spořitelna České spořitelny and sculptor Michal Trpak, the 43m2 house was printed in 22 hours, including its partitions, and used a total of 17 tons of concrete mixture. (3)
According to the company, compared to conventional passive houses, printed houses can save up to 50% of all costs and are built 7 times faster. Compared to brick buildings, 3D printing also generates up to 20% less CO2 emissions. The house was printed using a robotic arm through which a newly-developped concrete mixture – enriched with nano-polypropylene fibers and plasticizers that improve plasticity – flows directly to the destination. The robot prints at a speed of 15 centimeters per second. (3)
As the company highlights, this type of concrete hardens after 24 hours to the standard compressive strength of a typical family house foundation (i.e. 25 MPa). After full hardening in 28 days, the concrete acquires strength values (65 MPa) identical to those required for bridges. (3)
. At the IIR co-sponsored CYTEF online conference in November 2020, Spanish researchers presented an energy analysis of a small 3D-printed 24 m2 residential building located in Valencia (4). Based on the calculation of the thermal loads through detailed modelling of the dwelling, they defined a set of passive strategies to achieve the requirements needed to obtain NZEB certification.
They found that it was possible to reduce the cooling energy consumption from 44,41 kWh/m2.year to 14.99 kWh/m2.year and the heating energy consumption from 190.44 kWh/m2.year to 13.64 kWh/m2.year, where the Passivhaus criterion is 15 kWh/m2.year for cooling and heating. The redesign of the dwelling allows to avoid 1.23 tons of CO2 eq/year and the financial savings amount to about 280€/year.
Since some of the passive strategies defined – such as orientation of the façades – do not apply to already constructed buildings, this study is mainly intended to be useful in the context of the construction of new dwellings using 3D printing technology.
(4) REVERE V., MASIP X., PRADES-GIL C., BARCELO RUESCAS F. Energy analysis of a 3D printed building and energy improvement to achieve near zero energy building. In VIII Ibero-american congress on refrigeration sciences and technology, CYTEF 2020. See in FRIDOC (15 euros for IIR members).