Researchers at the Tallinn University of Technology (TUT) are working on a project focused on the solutions and examples of nZEBs as well as the sustainable and cost-effective energy-renovation of dwellings to low-energy level. Better indoor climate and energy performance, lessening environmental impact, cost-effectiveness, and longer service life will be taken into account in finding solutions for nZEB and deep renovation.
Professor Targo Kalamees, project leader and head of the Chair of Building Physics and Energy Efficiency in TUT, said that increasing the energy performance of buildings is one of the most effective ways to increase energy independence, and a good way to reduce greenhouse gas emissions responsible for climate change. “The improvement of existing buildings offers a huge potential for energy saving. This enormous potential is present in more than two thirds of existing buildings,” Kalamees explained.
nZEB will help solve Problems of Passive Houses
The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources. “nZEB is now seen as the real target in the design of buildings. nZEB are no longer viewed as a concept belonging to the remote future but as a realistic solution for the reduction of energy use in the built environment and the mitigation of consequent CO2 emissions,” Kalamees said. “nZEB buildings generally require the improved performance of components and systems, system integration for the utilization of passive means, and integrated design for the whole building’s better performance,” he added.
At the moment there is a lack of good examples on nZEB and limited information on how to build them as well as on how to renovate buildings to nZEB level in a sustainable and cost-effective manner, Kalamees said. “The construction and renovation of buildings to a higher energy performance level presupposes that a wide range of technical, economic, architectural and behavioural requirements are fulfilled,” Kalamees explained. “These aspects are connected and often involve contradictory measures, which justifies pursuing inter-disciplinary research to develop knowledge and get a comprehensive and holistic understanding of the effect of different energy upgrade measures. Obviously, both new and existing buildings are extremely important in tackling energy performance targets,” he said.
During the project researchers of TUT study the typical mistakes of low energy buildings (such as passive houses) and try to avoid similar mistakes in nZEB. Typical shortcomings are, for example, overheating in summer and insufficient heating in winter because of the lack of capacity or individual control in the rooms; need for both heating and cooling (despite of very low net energy) achieved with effective demand reduction measures; heating and cooling capacity peak loads reduced less compared to standard buildings.
Cost-effectiveness and Sustainability
Kalamees explained that highly insulated external walls need thick insulation, which is, as such, sensitive to moisture and drying in the construction stage. “The insulation thicknesses needed for nZEB are suitable in a cold climate because highly insulated building envelopes have caused specific moisture safety and durability problems,” he said.
The subject is very topical in Estonia as most buildings are privately owned—even apartments have independent owners—, and it would be hard to demolish these buildings. So, the sustainable solution is the only option. “To ensure the true cost-effectiveness of renovation works and adequately activate market forces, building renovations must correspond to deep renovation standards, which will be developed in the current project,” Kalamees concluded.
As the topic of the project is interdisciplinary, the team includes professions of different specialities: building physics, renovation of buildings, indoor climate, energy performance of buildings, buildings’ service systems, materials science, building technology. Other professors involved in this research are Jarek Kurnitski, Irene Lill, Teet-Andrus Kõiv, and Urve Kallavus.
 Nearly-zero energy solutions and their implementation on deep renovation of buildings https://www.etis.ee/Portal/Projects/Display/0cd8a8e3-196b-4d20-8556-5dec487fbf43
This article was funded by the European Regional Development Fund through Estonian Research Council.