Estonia has a long-term renovation strategy target of 14,000 renovated apartment building in 2020-2050. The KredEx renovation grant system has brought on significant results in deep renovation. Since the first scheme of the grant system, there are improvements in ventilation requirements.
Estonia has achieved great results in deep renovation, thanks to the KredEx renovation grant system. Backed by the EU since its 2010 kick-off, KredEX features strict technical requirements, focusing on high-level energy efficiency and indoor climate conditions.
Large-scale renovation has generated positive effects on the macroeconomic level, quantified in terms of job creation and tax return. All in all, 17 jobs per 1 million euros of investment in renovation have been created directly and indirectly per year in Estonia. Tax revenue from renovation construction projects has been quantified to be 32–33 % of the total renovation project costs. Therefore, evidence from Estonia shows that a state subsidised renovation has been, in practical terms, budget neutral with direct financial support of 25–40 % used in last 10 years.
During this decade, around 1,100 apartment buildings have been renovated. Energy efficiency and indoor climate conditions comparable to modern apartment buildings have been achieved with deep integrated renovation. At the same time, it’s worth taking note that the cost of deep renovation is approximately 3–4 times lower than building a new apartment building. This is a good start, but the volume needs to be increased to catch the long-term renovation strategy target of 14,000 renovated apartment building in 2020-2050.
Challenges in indoor climate quality during the first scheme
Support from the EU first materialised in 2010-2014, as a total of 663 apartment buildings underwent renovation in Estonia. This first period showed what can go wrong and what needs to be improved in renovation. Typical to any new scheme, KredEx started with well-defined energy saving targets, but technical requirements for ventilation were not specified. It was just stated that indoor climate quality should follow Category II indoor climate target values typically used in new buildings according to European standard. In reality, such general requirement was not followed and many ventilation solutions failed. That especially applied for single room ventilation units with heat recovery which were noisy, had frost problems and were overrun by stack effect in high-rise buildings.
Developed scheme with new ventilation requirements
Crucial development was made in the new grant scheme, KredEX II, emerged for 2015-2017, with a total of 102 million euros in EU Structural Funds used. Under this new scheme, technical requirements and the application process were further developed and more detailed. Now the starting point was that heat recovery ventilation systems are to be installed in order to achieve substantial energy savings (about 70% in heating) and indoor climate improvements at the same time. For that purpose, two technical ventilation solutions were specified for a common large renovation grant (35% support at that time). These solutions were mechanical supply and exhaust ventilation with heat recovery or ventilation radiators with exhaust air heat pump. Both systems have been widely used. There was a significant innovation to install ventilation ductwork to façade into new additional insulation layer that made centralized heat recovery ventilation feasible. Exhaust air heat pump with ventilation radiators has been popular in higher buildings where main ducts become bigger and are more challenging to install to façade. Together with ventilation system specification, ventilation airflow requirements were set on room level, telling how much supply air is needed in bedrooms and living rooms and how much extract from toilets, bathrooms and kitchens. These new requirements made design transparent, KredEx also started to evaluate the compliance of design documentation by external consultants. Finally, the airflow measurement protocol requirement after installation ensured that ventilation was well done in all projects.
The same technical requirements have been used during last years, but now the scheme has developed with regional development considerations. While a large grant in Tallinn and Tartu was limited to 30% support, projects in smaller cities received 40% and in Ida Virumaa even 50%.
Jarek Kurnitski, professor at the Tallinn University of Technology, is a distinguished researcher in the field of energy performance and indoor climate of buildings.