Heat production and cooling
1. Interim report: Analysis of current situation
Heat consumption for heating (and hence production), and the need for cooling depend directly on the weather conditions one has on their latitude. This sector is mostly affected by the ambient air temperature, but important factors are also wind speed, solar radiation intensity and humidity in the air. The lower the ambient air temperature, the higher the need to heat the indoor facilities in order to ensure room temperatures desired by people. The higher wind speeds and higher air humidity too increase the heat consumption. In Estonia, the question of indoor space heating is more important than cooling which so far has received less attention. Increased rainfall may cause more flooding, which in turn can be associated with basement flooding of the buildings and could therefore damage the automation of heat supply stations. The higher groundwater levels and increased soil moisture results in higher heat loss, especially in old non-insulated heat pipes, because the thermal conductivity of the soil increases. This effect is relatively small in case of modern pre-insulated pipes. Due to shortened heating period, the losses in the heat transmission will increase, which will be used to heat the domestic hot water during the periods when heating is not necessary.
Restructuring of heat production and consumption have been held due to the restructuring of the economy and the housing, as well as due to demographic changes (urbanization). The effects of climate factors on the cause of the changes happened in these areas are non-existent. However, district heating is more sensitive to climate changes than the block heating since the climate warming can result to the decrease in the consumption of heat which in turn can make the management of district heating networks economically inexpedient. Historically, the long lasting high air temperatures have occurred rather rarely in Estonia. The maximum ambient air temperature of +30 and higher, during five or more days, has been considered to be hazardous to human health. Such a situation has occurred only three times in the period between the years of 1961-2010. During the periods of high air temperatures, the most commonly used premises used for cooling are the windows kept open in the evenings and at night, to draw out the free heat which has accumulated in the building during the day. At noon, when there is typically the highest temperature of the day, the windows are kept closed. What helps to align the temperature are also the massive peripheral structures of the buildings. In Estonia, local electric cooling equipments are in use - fans, air conditioners and heat pumps. With the rise of the average air temperatures, their usage increases. It is expected that in the future, the passive engineering techniques will be used for cooling of the buildings, similarly to what are today used in the Mediterranean countries: screens and shields on the windows, ventilation gaps in the walls and anything alike.
2. Interim report: Climate change impact assessment (including analysis of possible risks and vulnerability)
Heating and cooling is mostly affected by outdoor temperature changes and trends, other climate parameters and their changes have only indirect effects on this field. The influences that climate change will entail, and which are assed in this chapter, are based on the report „Future climate scenarios of Estonia until 2100“. The following assessments are only valid when the scenarios in the forementioned report become reality.
The temperature during the heating period has direct effects on consumption volume, transportation losses, efficiency and neccessary power to cover peak demand. An important aspect to the resilience of the heating and cooling sector is the energy efficiency of the building stock. Buildings with higher efficiency are generally less affected by climate changes. Cooling is mostly affected by heatwaves in the summer, but also by direct sunlight and wind speeds. The vulnerability of cooling devices and the related infrastructure reveals with exceptional weather conditions, like the forementioned heatwaves, but also weather events like storms that disrupt the electricity supply. During the reference years the period with residential cooling demand was significantly shorter than the heating period. Due to the climate changes the difference decreaeses, but the heating period will remain longer than the cooling period, even in the end of the evaluation period.