planning:non-residential_passive_house_buildings:passive_house_retail

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planning:non-residential_passive_house_buildings:passive_house_retail [2018/04/23 15:03]
kdreimane [Retail stores and energy efficiency]
planning:non-residential_passive_house_buildings:passive_house_retail [2018/04/23 15:20] (current)
kdreimane [Thermal protection]
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 \\ \\
 ==== Food refrigeration ==== ==== Food refrigeration ====
 +[{{ :picopen:01_pb40_einfuehrung_en_abb.2.png?400|**Figure 2: Heat dissipated by the refrigeration installation is disposed of towards the outside so that internal heating loads can be limited.**}}] 
 +In the food sector in smaller retail stores in particular, the electricity consumption for food refrigeration accounts for about half of the total electricity consumption. As demonstrated in the article about food refrigeration in retail stores //(soon on Passipedia)//, there is a large savings potential in this area; from the technical and physical standpoint, it seems that an overall factor of 10 can be achieved, which is similar to that realised in residential buildings for heating energy! \\
  
-In the food sector in smaller retail stores in particular, the electricity consumption for food refrigeration accounts for about half of the total electricity consumption. As demonstrated in the article about food refrigeration in retail stores //(soon on Passipedia)//, there is a large savings potential in this area; from the technical and physical standpoint, it seems that an overall factor of 10 can be achieved, which is similar to that realised in residential buildings for heating energy! \\ 
-\\ 
-|{{:picopen:01_pb40_einfuehrung_en_abb.2.png?400}}|\\ 
-|//**Figure 2: \\ Heat dissipated by the refrigeration installation is disposed of \\ towards the outside so that internal heating loads can be limited.**//|\\ 
-\\ 
 The refrigerated shelves withdraw considerable amounts of heat from the room, which, at least in part, is usually extracted towards the outside by means of a refrigeration installation with central cooling (Figure 2). Thus the heating loads caused by the refrigeration itself do not accumulate inside the thermal envelope. Plug-in freezers are especially popular in the frozen food section for practical reasons (lower investment and running costs, greater safety of goods in case of failure of individual freezers, the resultant lower demand for reliability of the individual appliances, flexibility of location, easier adaptation to altered requirements and seasons). Heat dissipated by these appliances is directly released into the surrounding area. If the ratio of both types of cooling is correct, the store will not need any active cooling, despite the high loads caused by the lighting (see below). At the same time, the temperatures in front of the refrigerated shelves will not fall to the extent that customers are negatively affected. \\ The refrigerated shelves withdraw considerable amounts of heat from the room, which, at least in part, is usually extracted towards the outside by means of a refrigeration installation with central cooling (Figure 2). Thus the heating loads caused by the refrigeration itself do not accumulate inside the thermal envelope. Plug-in freezers are especially popular in the frozen food section for practical reasons (lower investment and running costs, greater safety of goods in case of failure of individual freezers, the resultant lower demand for reliability of the individual appliances, flexibility of location, easier adaptation to altered requirements and seasons). Heat dissipated by these appliances is directly released into the surrounding area. If the ratio of both types of cooling is correct, the store will not need any active cooling, despite the high loads caused by the lighting (see below). At the same time, the temperatures in front of the refrigerated shelves will not fall to the extent that customers are negatively affected. \\
  
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 The EN 12464 standard stipulates an illuminance of 300 lx. With state of the art technology, this can be ensured with an installed output of about 5 W/m². In order to present (supposed or actual) goods in an optimal manner, the actual installed outputs are often much higher with around 30 W/m², and illuminance levels may even be higher than 1000 lx. In grocery stores this leads to about one quarter of the total electricity consumption being used for lighting, and the amount may be even higher in other areas. \\ The EN 12464 standard stipulates an illuminance of 300 lx. With state of the art technology, this can be ensured with an installed output of about 5 W/m². In order to present (supposed or actual) goods in an optimal manner, the actual installed outputs are often much higher with around 30 W/m², and illuminance levels may even be higher than 1000 lx. In grocery stores this leads to about one quarter of the total electricity consumption being used for lighting, and the amount may be even higher in other areas. \\
 \\ \\
-|{{:picopen:01_pb40_einfuehrung_en_abb.3.png?600}}|\\ +[{{ :picopen:01_pb40_einfuehrung_en_abb.3.png?450|**//Figure 3: Even if windows exist, lights are almost always in use regardless of the availability of natural light.//**}}]
-|**//Figure 3: \\ Even if windows exist, lights are almost always in use regardless of the availability of natural light.//**|\\+
 \\ \\
 The most efficient lamps and lights are normally not used; instead lights that promise an optimal presentation of goods are used. The use of daylight for some part of the day, which would appear to be appropriate in view of store opening times, has hardly ever been observed in practice. Even if daylight is available, artificial lighting is not reduced, either for technical reasons or to avoid affecting the presentation of goods (Figure 3). In grocery stores, use of daylight is also made difficult by the fact that foodstuffs without packaging deteriorate much more quickly when exposed to direct sunlight. \\ The most efficient lamps and lights are normally not used; instead lights that promise an optimal presentation of goods are used. The use of daylight for some part of the day, which would appear to be appropriate in view of store opening times, has hardly ever been observed in practice. Even if daylight is available, artificial lighting is not reduced, either for technical reasons or to avoid affecting the presentation of goods (Figure 3). In grocery stores, use of daylight is also made difficult by the fact that foodstuffs without packaging deteriorate much more quickly when exposed to direct sunlight. \\
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 ==== Thermal protection ==== ==== Thermal protection ====
 +[{{ :picopen:01_pb40_einfuehrung_en_abb.4.png?250|**Figure 4: Display windows of existing buildings often still have single glazing.**}}]
  
 Like other efficiency measures, thermal protection has played a rather subordinate role in retail stores up till now (see e.g. Figure 4). Not only is it disregarded but sometimes it is even viewed critically: in buildings with sufficiently high internal heating loads, the issue arises whether a good level of thermal protection would be productive all at all, or whether it would be better to deliberately induce the maximum possible transmission losses in order to reduce the cooling demand. \\ Like other efficiency measures, thermal protection has played a rather subordinate role in retail stores up till now (see e.g. Figure 4). Not only is it disregarded but sometimes it is even viewed critically: in buildings with sufficiently high internal heating loads, the issue arises whether a good level of thermal protection would be productive all at all, or whether it would be better to deliberately induce the maximum possible transmission losses in order to reduce the cooling demand. \\
      
 In actual fact, further improvement of the thermal protection is pointless and will lead to an increased cooling demand, at the latest when the internal heat gains meet the maximum heating demand (Figure 5). \\ In actual fact, further improvement of the thermal protection is pointless and will lead to an increased cooling demand, at the latest when the internal heat gains meet the maximum heating demand (Figure 5). \\
-\\ + 
-|{{:picopen:01_pb40_einfuehrung_en_abb.4.png?400}}|\\ +[{{:picopen:01_pb40_einfuehrung_en_abb.5.png?450|**Figure 5: Useful energy demand of a supermarket (similar to Figure 1) for heating and cooling with different internal heat sources.** 
-|//**Figure 4: \\ Display windows of existing buildings \\ often still have single glazing.**//|\\ +An x-axis value of 0 shows the level of insulation required according to the German EnEV standard. The cooling demand is greater with higher internal loads, more insulation will then be contraproductive. Figure 7 demonstrates that additional natural ventilation in summer can solve this problem.}}] 
-\\ +
-|{{:picopen:01_pb40_einfuehrung_en_abb.5.png?500}}|\\ +
-|//**Figure 5: \\ Useful energy demand of a supermarket (similar to Figure 1) for heating \\ and cooling with different internal heat sources.** \\ \\ An x-axis value of 0 shows the level of insulation required according to the \\ German EnEV standard. The cooling demand is greater with higher internal loads, \\ more insulation will then be contraproductive. Figure 7 demonstrates that additional \\ natural ventilation in summer can solve this problem.//|\\ +
-\\+
 Since internal heat gains are a decisive influencing parameter for the concept of the structural envelope, these will be examined in more detail here. Figure 6 illustrates how great the fluctuations in the heat gains can be in retail stores. \\ Since internal heat gains are a decisive influencing parameter for the concept of the structural envelope, these will be examined in more detail here. Figure 6 illustrates how great the fluctuations in the heat gains can be in retail stores. \\
  
 Four full-range retail store variants are shown on the left. The variant "old" shows a market with inefficient lighting (installed output ca. 25 W/m²) and other equipment resulting in average heat dissipation of more than 20 W/m² into the room. On the other hand, an average of 50 W/m² of heat is withdrawn from the room by the open refrigerated shelves with poor air curtains and without roll-down night covers, so that there are net internal heat losses of more than 30 W/m² in the end. The total electricity consumption amounts to 640 kWh/(m²a). Additional air conditioning in summer is not required, instead the store has to be heated almost all year round to compensate for the heat that is withdrawn. \\ Four full-range retail store variants are shown on the left. The variant "old" shows a market with inefficient lighting (installed output ca. 25 W/m²) and other equipment resulting in average heat dissipation of more than 20 W/m² into the room. On the other hand, an average of 50 W/m² of heat is withdrawn from the room by the open refrigerated shelves with poor air curtains and without roll-down night covers, so that there are net internal heat losses of more than 30 W/m² in the end. The total electricity consumption amounts to 640 kWh/(m²a). Additional air conditioning in summer is not required, instead the store has to be heated almost all year round to compensate for the heat that is withdrawn. \\
-\\ +
-|{{:picopen:01_pb40_einfuehrung_en_abb.6.png?500}}|\\ +
-|**//Figure 6: \\ Variation range of the internal heat gains. \\ TK = deep freezing, NK = Normal cooling//**|\\ +
-\\+
 With the standard equipment commonly used nowadays, consisting of roll-down night covers in front of the refrigerated shelves and lighting using T8 lamps with an installed output of 10 W/m², the electricity consumption is just 260 kWh/(m²a), and heat withdrawal is already significantly less. Heat flows can be controlled even more easily if the best technology available today is used with moderate levels of illuminance, in accordance with the "good" scenario. For the "future" variant, one would expect optimised refrigeration equipment and reduced electricity consumption for lighting, even if the levels of illuminance are increased. If the efficiency of the bakery section and other electrical applications is also improved at the same time, then the internal gains will amount to just a few watts per square metre. Depending on the level of illuminance and the proportion of refrigeration equipment, this may be positive or negative. \\ With the standard equipment commonly used nowadays, consisting of roll-down night covers in front of the refrigerated shelves and lighting using T8 lamps with an installed output of 10 W/m², the electricity consumption is just 260 kWh/(m²a), and heat withdrawal is already significantly less. Heat flows can be controlled even more easily if the best technology available today is used with moderate levels of illuminance, in accordance with the "good" scenario. For the "future" variant, one would expect optimised refrigeration equipment and reduced electricity consumption for lighting, even if the levels of illuminance are increased. If the efficiency of the bakery section and other electrical applications is also improved at the same time, then the internal gains will amount to just a few watts per square metre. Depending on the level of illuminance and the proportion of refrigeration equipment, this may be positive or negative. \\
  
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 If no frozen foods are being sold, then internal gains can even be more than 20 W/m² with high illuminance levels. At some point it will become necessary to use a high-performance air conditioning system with corresponding energy consumption in order to equalise the night/day fluctuations. \\ If no frozen foods are being sold, then internal gains can even be more than 20 W/m² with high illuminance levels. At some point it will become necessary to use a high-performance air conditioning system with corresponding energy consumption in order to equalise the night/day fluctuations. \\
 +
 +[{{:picopen:01_pb40_einfuehrung_en_abb.6.png?500|**Figure 6: Variation range of the internal heat gains. TK = deep freezing, NK = Normal cooling**}}]
 +
 +[{{:picopen:01_pb40_einfuehrung_en_abb.7.png?550|**Figure 7: As in Figure 5, but with an additional air change rate of 3 h<sup>-1</sup> for space cooling.**}}]
 +
 +----
  
 There are two aspects which need to be kept in mind with regard to the question of the appropriate level of thermal protection: the planned use of the building can change several times during the lifetime of the building envelope; adjustment of the sales concepts should at least be expected; the envelope should still continue to function. Significant improvements are expected in the next few years, particularly with reference to the efficiency of lighting (see the article "Daylight and artificial lighting" by Wilfried Pohl in the [[http://passiv.de/literaturbestellung/index.php/en/product/view/31/268|Protocol Volume No. 40]] of the "Research Group for Cost-effective Passive Houses"; //only available in German//). In addition, goods can be presented appropriately by means of well thought-out concepts for lighting, even with moderate illuminance levels. \\ There are two aspects which need to be kept in mind with regard to the question of the appropriate level of thermal protection: the planned use of the building can change several times during the lifetime of the building envelope; adjustment of the sales concepts should at least be expected; the envelope should still continue to function. Significant improvements are expected in the next few years, particularly with reference to the efficiency of lighting (see the article "Daylight and artificial lighting" by Wilfried Pohl in the [[http://passiv.de/literaturbestellung/index.php/en/product/view/31/268|Protocol Volume No. 40]] of the "Research Group for Cost-effective Passive Houses"; //only available in German//). In addition, goods can be presented appropriately by means of well thought-out concepts for lighting, even with moderate illuminance levels. \\
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 The second aspect is that an increased loss of heat can be achieved in summer by means of increased natural ventilation, whether at night or during the daytime. In all four cases studied here (Figure 7), if a three-fold air change rate is set then a better level of thermal protection no longer results in higher overall consumptions. Even so, limiting the internal heat gains naturally takes priority, firstly on account of the electricity consumptions itself, and secondly, in order to make it easier to achieve a comfortable indoor climate without draughts and with adequate air humidity in winter. \\ The second aspect is that an increased loss of heat can be achieved in summer by means of increased natural ventilation, whether at night or during the daytime. In all four cases studied here (Figure 7), if a three-fold air change rate is set then a better level of thermal protection no longer results in higher overall consumptions. Even so, limiting the internal heat gains naturally takes priority, firstly on account of the electricity consumptions itself, and secondly, in order to make it easier to achieve a comfortable indoor climate without draughts and with adequate air humidity in winter. \\
 \\ \\
-|{{:picopen:01_pb40_einfuehrung_en_abb.7.png?500}}|\\ +
-|Figure 7: \\ As in Figure 5, but with an additional air change rate of 3 h<sup>-1</sup> for space cooling.|\\+
 \\ \\
  
planning/non-residential_passive_house_buildings/passive_house_retail.1524488632.txt.gz · Last modified: 2018/04/23 15:03 by kdreimane