Case Study: nZEC - Energy refurbishment of 32 dwellings in Tartu Street, Võru, Estonia (UNDER MONITORING)

Short Description

The project was carried out because of high price for heat and uncomfortable indoor climate. Heating system was one pipe system with no possibility to regulate on the radiator level. Ventilation was designed as natural from windows, but due to the fact that most of the apartments have already changed windows the natural ventilation does not worked properly any more. Heating system was unbalanced and heat supply to the radiators was unstable. At the same time support scheme for renovation was available.

Scheme terms were connected with energy saving % compared with last 3 years consumption. Conditions - 35% investment support means 50% savings. Association general meeting decided to go on 35% investment support. Flat owners are in 49% pensioners with reasonable low income (about 300 EUR month). Conditions foreseen that renovation should consist from total insulation of all external walls (U value 0,2) and roof (U value 0,15), installation of windows with U value not higher than 1,1. Heating system should be regulated on the radiator level, ventilation should have heat recovery element, flat based system was decided to use. Renovation project was designed for these conditions.

Key Elements

Monitoring

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Funding

Main Results

• The most important is that flat owners got comfortable living with high quality indoor climate and with the same annual expenditure like before renovation.
• The apartment’s value is higher and house main constructions are now protected and there are no thermal bridges.
• Ventilation system will use exhaust air heat, heat consumption is expected to be 50% less than before.
• During the period from 2012, when the complex renovation was done, till 2014 the energy consumption for space heating drops from 140 kWh/m² to 57 kWh/m², means 59%.
  
  
  

Lessons learned

• The heat recovery technology Intelivent inverter heat recovery system is in use and first assessment of the first full year shows that these people who are using the system are satisfied with it as there is fresh air now  in the apartment and no mould an moisture anymore.
• Without the use of radiators the heat recovery system does not provide preheated inlet air and this may cause problems (cold fresh air inlet).
• Two pipe heating system with thermostatic valves on each radiator allows to regulate comfortable temperature in each room. Apartments are warmer and there is no unbalance in the heating system.
• New ventilation system had some difficulties for users, because there is a need for the heat exchanger to “charge” the heat accumulation part of the exchanger, but for some users this was not understood.
• If the water heating system battery is regulated with thermostatic valve on low position (+16 C) then the exchanger does not have the heat to charge the exchanger and inlet air will not warm on comfortable level and users feel could (+8 C) air inlet.
• Radiators should be regulated on +21 C and ventilation heat exchangers should run permanently, then the heat exchanger will charge and those problems are solved.
• The awareness of flat owners should be on the level before the refurbishment decision that they can understand the difference to live in not renovated and renovated apartment house.
  
  
  

Additional Information

Ms Anu Sarnet
EKÜL - The Estonian Union of Cooperative Housing Associations
E-mail: anu.sarnet@ekyl.ee
Web: www.ekyl.ee