CHANGES IN THERMAL ENERGY CONSUMPTION IN APARTMENT BUILDINGS OF ESTONIA Teet-Andrus Kõiv,

The biggest part of energy in Estonian housing sector is consumed by apartment buildings. These buildings have mostly one-pipe heating systems and central domestic hot water systems with towel driers on circulating pipe. About 65% of our apartment buildings are heated from district heating network. Part of the buildings are heated from local boiler houses, where gas is the most common fuel.

The approximate U-values of the non- renovated envelope elements of typical apartment buildings are: W/(m 2 K) External walls- 1.0 – 1.2 Roof-ceilings- 0.8 – 1.0 Windows – 3.0

Recommended U-values for envelope elements of new apartment buildings: W/(m 2 K) External walls Roofs Windows- 2.1

In the 70s of the last century, total heat energy consumption in apartment buildings in Estonia was relatively high, about 350 kWh/m 2 per year (per total apartment area). The domestic hot water energy consumption was about 145 kWh/m 2 per year (95 l/d per person) – the domestic hot water rate in apartment building energy consumption was 41%.

Trends in heat energy consumption in the years 1999…2004 The average heat energy consumption in apartment buildings decreased from 219 kWh/m 2 per year in 1999, to 206 kWh/m 2 in 2004, the decrease being only 6%. Special heat energy consumption for domestic hot water heating in apartment buildings decreased from 56 to 41 kWh/m 2 per year, the decrease constituted 27%.

Domestic hot water consumption trends in the years 1999…2004 Hot water consumption decreased from 60 l/d per person in 1999, to 44 l/d per person, in 2004.

Domestic hot water consumption rate in typical apartment buildings in 1974 was 95 liters per day per person. This is 2.2 times more than in Domestic hot water consumption in the US residential homes is l/d per person In apartment buildings in Russia it is about 85 l/per day per person. In Finland it is about 70 l/per day per person.

Domestic cold water consumption trends in the years 1999…2004. The total water consumption decreased from 129 l/d per person in 1999 to 98 l/d per person in 2004

The total water consumption in Tallinn in 2004 was 98 l/d per person. These data are close to water consumption in the housing sector of Belgium in 1998 and that of the Czech Republic and Bulgaria in Compared with that of Finland, our consumption is approximately 1.5 times less. The share of domestic hot water in total water consumption is 46% and has remained approximately the same in the last 6 years

Great changes in thermal energy and domestic hot water consumption have occurred during the last 30 years. Thermal energy consumption has decreased more than 40% - from 350 kWh/m 2 per year (in 1974) to 206 kWh/m 2 in Considerable changes have taken place in domestic hot water consumption, falling from 6.6 l/d per m 2 (in 1974) to 2.0 l/d per m 2 in As to thermal energy consumption the respective fall was from 144 to 41 kWh/m 2 per year in 2004, i.e. 3.3 times.

The main reasons for a decrease in domestic hot water consumption in Tallinn apartment buildings in recent years are: consumption metering in apartments; already high and still rising prices of water and heat; extensive renovation of domestic hot water systems, including circulation renovation; use of modern equipment (taps, showers).

For energy saving in apartment buildings is essential:  analyses of consumption  renovation of envelope elements  renovation of heating system: - hydronic balancing - control of heat output on the level of heating coils  renovation of windows and  renovation of ventilation

Heat requirements of apartment buildings for heating (per gross apartment area) The average difference between the apartment building heat requirements determined by simulation and by calculation on the basis of simple degree-days was 10% for the whole heating period

The average difference between the apartment building heat requirements determined by simulation and by calculation on the basis of simple degree- days was 10% for the whole heating period, the greatest difference 28%, occurring in May. This is due to the greatest solar radiation in May as compared to other months of the heating period. For spring and autumn months heat energy consumption calculations by simple degree-days method are not exact.

The simulation of heat requirements for a typical apartment building before and after the renovation of construction elements was carried out. The effect of external walls and roof insulation, windows renovation and rising control efficiency on heat requirements by simulation has been analyzed. The energy saving potential of old typical apartment buildings by renovation of envelope elements, rising control efficiency and renovation of equipment in Estonian conditions accounts for about 40-45%. For example in full renovated 72 apartment building thermal energy saving was about 43%.

The results of the analysis of heat losses of different envelope elements, natural ventilation and water heating in typical non-renovated apartment buildings

Special energy consumption in office buildings, schools and apartment buildings Left: Heat energy; right: heat energy and electricity per closed net area for office building,schools and apartment buildings

CONCLUSIONS During the past 15…20 years, there have been great changes in energy and water consumption in the Estonian housing sector. Thermal energy consumption has decreased by about 40%. The decrease in domestic hot water consumption in the last 30 years per gross area was more than 3 times.

Continued: The main reasons for a decrease in energy consumption of Estonian apartment buildings have been the following: high prices of water and heat and their continued increase; water consumption metering in apartments; extensive renovation of domestic hot water systems, including circulation renovation; use of modern equipment (taps, showers); renovation of heat substations; balancing of heating systems; partial renovation of envelope elements.

Continued: The energy saving potential of typical old apartment buildings by renovation of envelope elements, improved control efficiency and renovation of equipment in Estonian conditions accounts for about 40-50%.

Thank you!