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Laboratory of Heat Transfer and Environmental Engineering Department of Mechanical Engineering Aristotle University Thessaloniki The European Directive on the Energy Performance of Buildings and the need for enhanced Thermal Insulation Professor Agis M.Papadopoulos Tirana, 07.04.06 The role of a building with respect to climate and its inhabitants A building’s design should aim to provide comfort to its inhabitants, whatever the ambient conditions are. The balancing of climatic conditions in the indoor environment can be implemented either through an energy conscious design or/and by energy consuming devices (HVAC systems) Summer Sun Rain, snow, etc. Protection Wind exposure Decrease Ventilation Control to provide cooling and IAQ Humidity Disposal Winter Sun Temperature Isolation from ambient environment Daylighting Increase Solar Radiation Increase solar gains during winter Decrease solar gains during summer 2 Relation of indoor comfort and a building’s energy demand A building’s design should aim to provide comfort to its inhabitants, whatever the internal loads are. Solar gains & daylighting Shading Cooling Natural ventilation Heating Infiltration Heat transfer Lighting Mechanical ventilation Internal gains Comfort: Thermal Air quality Lighting Acoustic …………. 3 Indoor comfort and the human reaction A building’s design should aim to provide comfort to its inhabitants, keeping in mind the human needs. 4 Energy consumption in buildings 40% of energy consumption in the EU is in buildings of all kinds. 25% of CO2 emissions result from buildings. Electricity consumption is expected to double between 2000 and 2020 5 This is the main reason and philosophy behind… The new European Directive on the Energy Performance of Buildings (EPBD) or 2002/91/EC This is the main reason and philosophy behind… The new European Directive on the Energy Performance of Buildings (EPBD) or 2002/91/EC asks for four main things: - A detailed methodology to determine energy consumption - Final and primary energy consumption statement - Inspection of heating systems and air-conditioning systems - Energy certification of buildings EPBD: a systemic, generic approach A holistic and integrated consideration of the building: We determine the primary energy demand of the building! EPBD: a systemic, generic approach A whole set of new CEN standards to implement it EPBD: a systemic approach towards reducing energy consumption A four-phase approach EPBD: New CEN standards on Thermal Losses Calculations A typical construction practice in Greece. Up till now the calculation of the transmission heat transfer coefficient was calculated not taking into account the thermal bridges H D i Ai Ui k lk k j j Thus, the transmission heat transfer coefficient was calculated according to H D i Ai Ui EPBD: New CEN standards on Thermal Losses Calculations A new constructional approach will be required to cope with the implementation of the new standards and the following regulations. According to standard ISO 14683 the transmission heat transfer coefficient is calculated by H D i Ai Ui k lk k j j EPBD: New CEN standards on Thermal Losses Calculations 6m 10 m For the simple two storey building with the thermal bridges R, B, C, F the new calculation procedure determines … 5m R B C F EPBD: New CEN standards on Thermal Losses Calculations … HD = 148.15 W/K instead of * It is noted that the calculations were conducted for common material properties and included only the linear thermal bridges (and not the point) HD = 106 W/K Thus, linear thermal bridges account for the 28.5% of the total transmission heat transfer coefficient of the building. Otherwise, the inclusion of thermal bridges in the calculation increases the heat transfer coefficient of the building by almost 40%. EPBD: Indoor comfort and new CEN standard CEN/TC 156 WG 12 34 Free-running buildings, line A 32 Heated or cooled buildings C o Tc = 13.5 + 0.54 To 30 Neutral or comfort temperature For not air-conditioned buildings 28 A 26 24 B 22 20 18 Tn = To 16 14 12 -24 -22 -20 -18 -16 -14 -12 -10 -8 where Τc is the thermal comfort, and Το the ambient air temperature -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Monthly mean outdoor temperature o C EPBD: Indoor comfort and new CEN standard CEN/TC 156 WG 12 For fully air-conditioned buildings EPBD: Taking care of real life conditions Introducing the inspection of heating and A/C systems EPBD: Certifying the energy performance of buildings Who has to comply? All new buildings bigger than 1.000 m2 All public buildings All buildings to be sold or rented And how? Either as designed Or as built Valid for 10 years EPBD: Certifying the energy performance of buildings and setting the goals for an efficient policy If 200 kWh/m2 is the average consumption of the current building stock (class C), then 125 should be the aim for 50% of the buildings after 2005 (class A) If 100 kWh/m2 is the average consumption of a good current building (class C), then 75 should be the aim for 50% of the buildings after 2005 (class A) EPBD: Certifying the entire performance of the buildings’ indoor environment EPBD: A partial success is not enough Up till now, a building with poor thermal comfort conditions, due to the lack of thermal insulation could be “improved”, by means of higher energy consumption. Up till now, a building with poor indoor air quality could be “improved”, by means of increased ventilation and, therefore, higher energy consumption. Up till now, a building with high energy consumption could be “improved”, by reducing the heating or cooling provided, and hence reducing thermal comfort. This is no longer possible. Buildings have to be “honest” to their users, and this officially certified. 21 EPBD and thermal insulation Thermal insulation is still the most economic and efficient way to design and construct an energy thrifty building. Insulation materials are the key tool in that sense. This is demonstrated by the increasing thicknesses used in buildings, which also reflects in the growing sales of the branch. 22 EPBD and thermal insulation: The potential The greatest potential, also for existing buildings, lies within the reduction of thermal losses through the building’s shell – and also in the improvement of heating systems. Exploitable potential 60 kWh/m2 a . 23 EPBD and thermal insulation: the case study A real case study: 41 buildings in Northern Greece, with a climate almost identical to Albanian zones 1 and 2. 24 EPBD and thermal insulation: the case study Energy consumption with respect to the date of construction. . Heating and cooling consumption with respect to the heated surface 25 . EPBD and thermal insulation, not forgetting thermal comfort Thermal comfort conditions in winter are by and large good or acceptable – yet the energy cost is very high. Without it, comfort would be poor. In summer we have both problems: lack of comfort and high energy costs. 26 EPBD and thermal insulation: The real saving potential The average achievable saving on the average specific annual consumption is some 40 kWh or 20% of the current condition. 27 EPBD and thermal insulation: The economic aspect The latest increase in energy prices is a good reminder of how short-sighted the policy of the last years has been. 20% of the Greek population spends more than 10% of its income for energy – tendency rising! 28 Had the measures been carried out, their reduced pay back period would now become apparent. EPBD and thermal insulation: The problems The unsuitability of the densely built urban environment (An only partially existing problem) Lack of legislative obligations and incentives, complex legislative framework Lack of financial incentives (The two most frequently mentioned barriers) Lack of proven expertise and qualified professionals Unwillingness to abandon the ‘business as usual’ approach (The two less easily acknowledged reasons) Low energy prices (not anymore?) Lack of energy and environmental consciousness (The truly socio-political problems) All points mentioned are result of a FORESIGHT study carried out in Greek SMEs in 2004 EPBD and thermal insulation, not forgetting the exploding air-conditioning demand Estimated growth of Air Conditioning (cooling) in the EU (EECCAC study) 30 EPBD and thermal insulation, not forgetting the exploding air-conditioning demand Estimated growth of Room Air Conditioning in the EU (EERAC study) 31 EPBD and thermal insulation, not forgetting the exploding electricity demand In July 2005 the absolute peak monitored was 9,620 MW. At the same time the cost for providing the ‘upper 600’ MWs, that are used only for 20 days per year was estimated at something like 3,800 Euros / MW, compared 32 to the 1,300 of the base load. EPBD and thermal insulation, not forgetting the exploding electricity demand According to the Green Paper on energy efficiency (June 2005): The production of an electric kWh costs on average 0,12 € The production of an electric kWh peak load costs between 0,15 and 0,25 € The cost of saving this same kWh is only between 0,026 and 0,039 € 33 EPBD and thermal insulation, not forgetting the exploding electricity demand EPBD, thermal insulation and a rational, realistic policy Average energy consumption is increasing rapidly, due to increased thermal comfort demands, black and white appliances and electronic equipment. 300 250 kWh / m2 a 200 150 100 50 0 Consumption in 1985 Consumption Forecast 2005 Forecast 2005 (RUE) (BAU) in 1995 Space Heating - DHW Lighting A/C Equipment The most effective way to absorb this increase is to exploit the saving potential in space heating, A/C and DHW demand of new and older buildings. EPBD, thermal insulation and a certain goal This is the minimum aim that we must set, in order to be able to establish and maintain high living standards affordable by everyone.