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planning:non-residential_passive_house_buildings:building_automation [2023/11/13 16:26] – [Control of system temperature of heating] wolfgang.hasper@passiv.deplanning:non-residential_passive_house_buildings:building_automation [2024/06/06 13:05] (current) – yaling.hsiao@passiv.de
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 For the operation of ordinary non-residential buildings, the automation of important functions is a necessity without which economic operation cannot be achieved. Energy efficient, optimised operation of the building can also be ensured if this is properly designed and executed. It also includes the possibility of data collection on a wide scale for systematic operations monitoring. For the operation of ordinary non-residential buildings, the automation of important functions is a necessity without which economic operation cannot be achieved. Energy efficient, optimised operation of the building can also be ensured if this is properly designed and executed. It also includes the possibility of data collection on a wide scale for systematic operations monitoring.
  
-Away from these ideal concepts, actual project experiences are often disillusioning. The functions in building automation are not always satisfactory and, especially in Passive House buildings, often aren't adapted to the requirements of energy-efficient operation. For example, there is almost a conflict with traditional approaches in the area of ventilation systems with heat recovery. The commonly used bypass control targeting a specified supply air temperature of e.g. 20 °C, regardless of the other boundary conditions in the building and time of year leads to unnecessary ventilation losses on mild winter days. Balanced operation and adherence to planned operating times are central to overall efficiency, but are not always successfully realised. Unintentional summer heating and increased system losses due to poorly adjusted flow temperatures have also been identified in many monitored projects.+Away from these ideal concepts, actual project experiences are often disillusioning. The functions in building automation are not always satisfactory and, especially in Passive House buildings, often aren't adapted to the requirements of energy-efficient operation. For example, there is almost a conflict with traditional approaches in the area of ventilation systems with heat recovery. The commonly used bypass control targeting a specified supply air temperature of e.g. 20 °C, regardless of the other boundary conditions in the building and time of year leads to unnecessary ventilation losses on mild winter days and wastes a cooling potential in the summer. Balanced operation and adherence to planned operating times are central to overall efficiency, but are not always successfully realised. Unintentional summer heating and increased system losses due to poorly adjusted flow temperatures have also been identified in many monitored projects.
  
 A frequent point of disagreement with users as well as with the requirements for efficient operation is the control of shading systems when they are operated without regard to the season and individual preferences. A frequent point of disagreement with users as well as with the requirements for efficient operation is the control of shading systems when they are operated without regard to the season and individual preferences.
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 The frequently encountered parallel structure of partial automation systems of the various trade disciplines usually does not produce satisfactory results because the exchange of information between the subsystems is incomplete or even non-existent. For example, a shading system cannot react to the room temperatures or heating operation, or a ventilation system cannot reduce heat recovery at the right time in spring. The frequently encountered parallel structure of partial automation systems of the various trade disciplines usually does not produce satisfactory results because the exchange of information between the subsystems is incomplete or even non-existent. For example, a shading system cannot react to the room temperatures or heating operation, or a ventilation system cannot reduce heat recovery at the right time in spring.
  
-In addition, commissioning is also made more difficult since several usually quite different systems have to be understood, operated and optimised. The availability of data for operations monitoring is accordingly just as limited and spread over several sources. Simply the collation of data alone is a challenge.+In addition, commissioning is also made more difficult since several usually quite different systems have to be understood, operated and optimised. The availability of data for operations monitoring is accordingly just as limited and scattered across several sources. Simply the collation of data alone is a challenge.
  
 It is therefore expedient to set up a single, cross-discipline automation system. The thermal condition (more of which later) of the building can provide a useful parameter for the coordinated control and regulation of building functions. It is therefore expedient to set up a single, cross-discipline automation system. The thermal condition (more of which later) of the building can provide a useful parameter for the coordinated control and regulation of building functions.
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 In non-residential Passive House buildings, there is a favourable response with very little influence on energy consumption due to deviations. Extending the daily usage times has hardly any noticeable influence on the energy consumption. Nevertheless, setback periods outside of the times of use with back-up operation/standby mode at 17-18°C is effective to a smaller extent and can be useful given the typically long downtimes of non-residential buildings. The accordingly slightly higher heating load must then be taken into account; guidance on this is given in AkkP 51. In non-residential Passive House buildings, there is a favourable response with very little influence on energy consumption due to deviations. Extending the daily usage times has hardly any noticeable influence on the energy consumption. Nevertheless, setback periods outside of the times of use with back-up operation/standby mode at 17-18°C is effective to a smaller extent and can be useful given the typically long downtimes of non-residential buildings. The accordingly slightly higher heating load must then be taken into account; guidance on this is given in AkkP 51.
  
-Seasonally different control schemes of shading equipment is necessary in order to enable solar heat gains in the winter and to avoid overheating of rooms in the summer. A threshold value of approx. 150 W/m² (global radiation) on the façade plane is a reasonable guideline.+Seasonally different control schemes of shading equipment is necessary in order to allow solar heat gain in the winter and to avoid overheating of rooms in the summer. A threshold value of approx. 150 W/m² (global radiation) on the façade plane is a reasonable guideline.
  
 Demand-based control of lighting installations can save significant amounts of electrical energy if these have a low auxiliary energy demand, including that for standby mode. This can support, but cannot be a substitute for, attentive building planning for a high degree of daylight autonomy and optimised specialist lighting planning. Demand-based control of lighting installations can save significant amounts of electrical energy if these have a low auxiliary energy demand, including that for standby mode. This can support, but cannot be a substitute for, attentive building planning for a high degree of daylight autonomy and optimised specialist lighting planning.
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 A similar process should be followed in reversed order at the approach of autumn and winter. A similar process should be followed in reversed order at the approach of autumn and winter.
  
-In efficient buildings, the customarily used outdoor temperature is not a suitable basis for estimating processes inside the building. A dynamic model-based approach which takes into account all influences of the weather (especially outdoor temperature and solar radiation) in addition to the usage-related heat gains etc. is very complex and too rigid for changes in use. However, the building itself continuously integrates all influences in the temperature of the deep building mass (concrete core temperature). This represents a suitable (low-pass) filter for the more strongly fluctuating room temperatures, and provides clear indications of the long-term development.+In efficient buildings, the customarily used outdoor temperature is no longer a suitable basis for controlling the heating or estimating processes inside the building. 
 + 
 +A dynamic model-based approach which takes into account all influences of the weather (especially outdoor temperature and solar radiation) in addition to the usage-related heat gains etc. is very complex and too rigid for changes in use. 
 + 
 +However, the building itself continuously integrates all influences in the temperature of the deep building mass (concrete core temperature). This represents a suitable (low-pass) filter for the more strongly fluctuating room temperatures, and provides clear indications of the long-term development.
  
 This kind of control concept, based on directly measured concrete core temperatures, was successfully implemented in the FOS/BOS Erding school project and extensive monitoring was carried out with funding by the DBU (German Environment Foundation, Project Number 26170/02). The control concept proved to be very successful; the concrete core temperatures from a larger number of rooms were averaged and the thermal condition of the building was determined from the average temperature. By defining thresholds and hystereses, it was possible to switch automatically between heating, neutral and cooling mode: This kind of control concept, based on directly measured concrete core temperatures, was successfully implemented in the FOS/BOS Erding school project and extensive monitoring was carried out with funding by the DBU (German Environment Foundation, Project Number 26170/02). The control concept proved to be very successful; the concrete core temperatures from a larger number of rooms were averaged and the thermal condition of the building was determined from the average temperature. By defining thresholds and hystereses, it was possible to switch automatically between heating, neutral and cooling mode:
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 |Cooling: night-time ventilation|≥ 23,5 (23,4)| |Cooling: night-time ventilation|≥ 23,5 (23,4)|
  
-Any short-term alterations in the operating status were excluded due to the inertia of the building's thermal mass. Conversely, it was possible to respond automatically to unusual weather or usage phenomena such as late cold spells or increased internal heat gains without problem.+Any unwanted short-term alterations in the operating status were reliably avoided due to the inertia of the building's thermal mass. Conversely, it was possible to respond automatically to unusual weather or usage phenomena such as late cold spells or increased internal heat gains without problem.
  
  
 ==== Determining the thermal condition from measured room temperatures ==== ==== Determining the thermal condition from measured room temperatures ====
  
-Determination of the thermal condition from direct measurement of the concrete core temperature has proved to work well, but this measurement is relatively laborious because it requires an additional number of sensors which must be set up, maintained, calibrated and evaluated. However, the thermal condition for a room can be calculated with sufficient accuracy on the basis of the prevailing room temperature using a simple thermal model of a concrete ceiling.+Determination of the thermal condition from direct measurement of the concrete core temperature has proved to work well, but this measurement is relatively costly as it requires an additional number of sensors which must be set up, maintained, calibrated and evaluated. However, the thermal condition for a room can also be calculated with sufficient accuracy on the basis of the prevailing room temperature using a simple thermal model of a concrete ceiling.
  
 {{  :picopen:building_automation.png?700  }} {{  :picopen:building_automation.png?700  }}
  
-In this way, the desired information can be provided easily and cost-effectively. Data from a number of suitable model rooms are averaged and smoothed over a period of 24 hours in order to obtain the thermal condition of the building. The systems can be controlled according to this. In contrast to the approach used for the FOS/BOS Erding, more refined threshold values are defined which could look like this for example:+In this way, the desired information can be provided easily and cost-effectively, based on data from room sensors that are specified for general control purposes anyway. Data from a number of suitable model rooms are averaged and smoothed over a period of 24 hours in order to obtain the thermal condition of the building. The systems can be controlled according to this figure. Going beyond the approach used for the FOS/BOS Erding, more refined threshold values are defined which could look like this for example:
  
 ^Mode^24 h average building component temperature ϑThZ [°C] (hysteresis)| ^Mode^24 h average building component temperature ϑThZ [°C] (hysteresis)|
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 The temperature level in heating systems should be adapted to the demand in order to avoid unnecessarily high heat losses in heat generators and distribution systems, to allow condensation of water vapour from combustion processes, and to increase the coefficient of performance of heat pump systems. The temperature level in heating systems should be adapted to the demand in order to avoid unnecessarily high heat losses in heat generators and distribution systems, to allow condensation of water vapour from combustion processes, and to increase the coefficient of performance of heat pump systems.
  
-In intermittently operated non-residential buildings, the heating system is switched to back-up mode at night and on weekends for maintaining a minimum temperature of 17 °C, for example. Effectively, the heating system is switched off for this purpose, since in a Passive House building cools down slowly and does not reach this level within just a weekend. Back-up operation usually only becomes effective on the third or fourth day of interruption of use, i.e. on long weekends or during vacation periods. Heating is then only necessary again for heating up before the start of operations. This intermittent use results in a diurnal dynamic with the highest heating output demand in the early morning, which declines as the day progresses and often reaches a marginal limit around noon. This effect is particularly pronounced in schools and other buildings used by many people, and results from the use-related heat generated by the presence of many people, artificial lighting and computers etc.+In intermittently operated non-residential buildings, the heating system is switched to back-up mode at night and on weekends for maintaining a minimum temperature of 17 °C, for example. Effectively, the heating system is switched off for this purpose, since a Passive House building cools down only slowly and does not reach this level within just a normal weekend. Back-up operation usually only becomes effective on the third or fourth day of interruption of use, i.e. on long weekends or during vacation periods. Heating is then only necessary again for heating up before the start of operations. This intermittent use results in a diurnal dynamic with the highest heating output demand in the early morning, which declines as the day progresses and often reaches a marginal limit around noon. This effect is particularly pronounced in schools and other buildings used by many people, and results from the use-related heat generated by the presence of many people, artificial lighting and computers etc.
  
-For optimised operation of the heating system, exactly the required output should be available in each case, just matching the output requirement of the building. A minimised temperature of the medium in each case can significantly influence the coefficient of performance of a heat pump and also reduce fluegas losses in a condensing boiler. Due to the steep increase in Carnot efficiency at low temperature differences of the heat pump process, any improvement here tends to have a significant effect.+For optimised operation of the heating system, exactly the required output should be available in each situation, just matching the output requirement of the building. A minimised temperature of the medium can significantly influence the coefficient of performance of a heat pump and also reduce fluegas losses in a condensing boiler. Due to the steep increase in Carnot efficiency at low temperature differences of the heat pump process, any improvement here tends to have a significant effect.
  
-In order to achieve a thermodynamic advantage at the heat generator, the forward flow temperature should not be controlled via return flow addition/mixing. Instead, the generator should always provide only the required temperature. Unless there is a particularly high demand for hot water, decentralised hot water generation with electric instantaneous water heaters is often a favourable solution in non-residential buildings. But even in centralised systems, the heat generator should provide high temperatures only for a short time for hot water generation.+In order to achieve a thermodynamic advantage at the heat generator, the forward flow temperature should never be controlled via return flow addition/mixing. Instead, the generator should always provide only the required temperature. Unless there is a particularly high demand for hot water, decentralised hot water generation with electric instantaneous water heaters is often a favourable solution in non-residential buildings and avoids a driver for high temperature in the main heating system. But even in centralised systems, the heat generator should provide high temperatures only for a short time for hot water generation.
  
-The simple and generally established control of the heating medium temperature based on the outdoor temperature using a control curve is not suitable for Passive Houses since due to the high thermal time constant of the building and the large influence of free heat, only a very weak correlation of the heating output with the outdoor temperature remains. Since many heat generators do not have an alternative control option, in the past the only easy possibility here was often a setting of the characteristic curve that was as flat as possible and sufficiently shifted in order to provide a quasi-constant flow temperature. Thus the possibilities of adapting to the demand remain unused, of course.+The simple and generally established control of the heating medium temperature is based on the outdoor temperature using a control curve. It is not suitable for Passive Houses since due to the high thermal time constant of the building and the large influence of free heat, only a very weak correlation of the heating output with the outdoor temperature remains. Since many heat generators do not have an alternative control option, in the past the only easy possibility here was often a setting of the control curve that was as flat as possible and sufficiently shifted up in order to provide a quasi-constant flow temperature. Thus the possibilities of adapting to the demand remain unused, of course.
  
 {{  :picopen:building_automation_2.png?1000  }} {{  :picopen:building_automation_2.png?1000  }}
  
-In the illustration above, the flow temperature setpoint (red) is controlled quite conventionally according to a characteristic curve based on the mixed outdoor temperature. The correlation with the actually required heating output (orange, right axis) is often inconsistent. In some time periods, the forward flow temperature appears higher than necessary (e.g. regularly in the second half of the week), whereas in the heating-up phases after the interruption of operation at the weekend it is sometimes likely too low.+In the illustration above, the flow temperature setpoint (red) is controlled quite conventionally according to a control curve based on the mixed outdoor temperature. The correlation with the actually required heating output (orange, right axis) is often inconsistent. In some time periods, the forward flow temperature appears higher than necessary (e.g. regularly in the second half of the week), whereas in the heating-up phases after the interruption of operation at the weekend it is sometimes likely too low.
  
-If the thermal condition of the building is known, it can be used as an input value for characteristic curve control of the temperature of the medium. This already leads to a much improved correlation with the actual output demand. In its simplicity, this characteristic curve method is certainly not optimal: short-term heat gains, especially from solar radiation, cannot be directly compensated. However, if the heating system is also switched off for the rest of the day when the pump speed falls below a minimum, i.e. when the flow rate is marginal, even this simple approach can work well.+If the thermal condition of the building is known, it can be used as an input value for the control curve of the temperature of the medium. This already leads to a much improved correlation with the actual output demand. In its simplicity, this improved control curve method is certainly not optimal: short-term heat gains, especially from solar radiation, cannot be directly compensated. However, if the heating system is also switched off for the rest of the day when the pump speed falls below a minimum, i.e. when the flow rate is marginal, even this simple approach can work well.
  
 {{  :picopen:building_automtation_3.png?1000  }} {{  :picopen:building_automtation_3.png?1000  }}
  
-The second figure shows an example of the flow temperature setpoint (red) determined according to a characteristic curve based on the thermal condition (grey). The required heating output is plotted at the bottom in orange, with reference to the Y-axis on the right. Compared to the outdoor temperature-related approach in the previous figure, a significantly improved correlation of the provided system temperature and required heating output can be seen. This already appears quite promising as long as the heating system is switched off during the weekends.+The second figure shows an example of the flow temperature setpoint (red) determined according to a control curve based on the thermal condition (grey). The required heating output is plotted at the bottom in orange, with reference to the Y-axis on the right. Compared to the outdoor temperature-related approach in the previous figure, a significantly improved correlation of the provided system temperature and required heating output can be seen. This already appears quite promising as long as the heating system is switched off during the weekends.
  
-Real output-based control that always provides only the minimum forward flow temperature for supplying the critical room is ideal. It must be assessed in each individual case whether the additional effort compared to the characteristic curve method based on the thermal condition justifies the expense. Possibilities here include regulation according to the measured heating surface temperatures, valve positions of the thermostatic valves or the cooling rate of the heating water, which usually requires some additional effort for data acquisition. The upturn in electronic data collection and transmission offers far-reaching new possibilities here, which should, however, always be evaluated against the background of reliable functioning over decades.+True output-based control that always provides only the minimum forward flow temperature for supplying the critical room is ideal. It must be assessed in each individual case whether the additional effort compared to the characteristic curve method based on the thermal condition justifies the expense. Possibilities here include regulation according to the measured heating surface temperatures, valve positions of the thermostatic valves or the cooling rate of the heating water, which usually requires some additional effort for data acquisition. The upturn in electronic data collection and transmission offers far-reaching new possibilities here, which should, however, always be evaluated against the background of reliable functioning over decades.
  
  
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 ===== Shading ===== ===== Shading =====
  
-Movable shading elements are particularly conspicuous to building users and their (often noisy) movement is often perceived as annoying. In addition, individual preferences of different users must be balanced with operation of the shading appropriate to the season. Well-designed control and regulation is therefore of particular importance for user acceptance and building function.+Movable shading elements are particularly conspicuous to building users and their (noisy) movement is often perceived as annoying. In addition, individual preferences of different users must be balanced with operation of the shading appropriate to the season. Well-designed control and regulation is therefore of particular importance for user acceptance and building function alike.
  
-Depending on the thermal condition of the building, solar heat gains are either desirable or to be avoided. Seasonal differentiation (determination of the seasonal operating mode) is therefore absolutely necessary. If solar gains are desired, the shading will always remain open. However, a possibility for user intervention is urgently required for the reasons mentioned above in order to take into account different preferences or requirements. It has proven effective to allow such user interventions for a limited time and then revert to the automatic signal again. A period of 2-3 hours avoids excessive domination of users, but also ensures proper building operation.+Depending on the [[https://passipedia.org/planning/non-residential_passive_house_buildings/building_automation#concepts_for_automation_in_non-residential_passive_house_buildings|thermal condition]] of the building, solar heat gains are either desirable or to be avoided. Seasonal differentiation (determination of the seasonal operating mode) is therefore absolutely necessary. If solar gains are desired, the movable shading device will normally remain open. However, a possibility for user intervention is urgently required for the reasons mentioned above in order to take into account different preferences or requirements. It has proven effective to allow such user interventions for a limited time and then revert to the automatic signal again. A period of 2-3 hours avoids excessive patronising of users, but also ensures proper building operation.
  
-If solar gains are to be avoided, the shading device is automatically closed when a threshold value for irradiation of approx. 150 W/m² (global radiation, ~ 15 kLux) is exceeded on the façade in question. On the other hand, user intervention is possible at any time for a limited period of time. If automatic operation is deployed again at fixed times then 06:00, 09:00, 12:00 etc. may constitute a reasonable framework.+If solar gains are to be avoided, the shading device is normally closed when a threshold value for irradiation of approx. 150 W/m² (global radiation, ~ 15 kLux) is exceeded on the plane of the façade in question. On the other hand, user intervention is again possible at any time for a limited period of time.
  
-It always makes sense split control of the shading devices at least with regard to the storey and orientation. If there is shading of the façades from neighbouring buildings, a critical elevation angle can also be included.+If automatic operation is deployed again at fixed times then a schedule of 06:00, 09:00, 12:00 etc. may constitute a reasonable framework. 
 + 
 +It always makes sense to split control of the shading devices at least with regard to the storey and orientation. If there is shading of the façades from neighbouring buildings, a critical elevation angle can also be included. Solar position algorithms used in shading controls supply the actual value.
  
 The selection of a shading system that provides sufficient daylight is an additional planning aspect. The selection of a shading system that provides sufficient daylight is an additional planning aspect.
  
-Regulation should be based on measured values from a high-quality sensor that is calibrated in an appropriate manner. Only then can reliable functioning be expected in the long term. A global radiation sensor (horizontal) is appropriate in case of operations monitoring, the measured values can then also be processed into monthly values for irradiation at that location.+Regulation should be based on measured values from a high-quality sensor that is calibrated in an appropriate manner. Only then can reliable functioning be expected in the long term. A global radiation sensor (horizontal) is appropriate in case of operations monitoring, the measured values can then also be processed into monthly values for irradiation at that site.
  
  
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 Interconnectivity of building automation components is an essential prerequisite for functioning as a system. The amount of energy used for operation of the connected components (storey distributors/switches etc.) is considerable. Both the investment costs as well as the operating costs for the systems are significant, even though building automation systems have low bandwidth requirements for the most part. It therefore makes sense to integrate the building automation into the physical IP network infrastructure which is already necessary in any case in order to achieve a high level of utilisation of the system instead of having to operate two systems in parallel. Interconnectivity of building automation components is an essential prerequisite for functioning as a system. The amount of energy used for operation of the connected components (storey distributors/switches etc.) is considerable. Both the investment costs as well as the operating costs for the systems are significant, even though building automation systems have low bandwidth requirements for the most part. It therefore makes sense to integrate the building automation into the physical IP network infrastructure which is already necessary in any case in order to achieve a high level of utilisation of the system instead of having to operate two systems in parallel.
  
-==== Heat generation ====+==== Waste heat ====
  
 Secondary effects also arise with improved efficiency of the building automation components. The lower operating costs with the reduced power consumption are obvious, but planning and execution can also become easier with lower heat loads. Switch cabinets do not have to be ventilated or even cooled, and a more compact design becomes possible. The service life of electronic components is also extended as the surrounding temperature falls. Secondary effects also arise with improved efficiency of the building automation components. The lower operating costs with the reduced power consumption are obvious, but planning and execution can also become easier with lower heat loads. Switch cabinets do not have to be ventilated or even cooled, and a more compact design becomes possible. The service life of electronic components is also extended as the surrounding temperature falls.
  
 The guiding principle for new development could be: "Every circuit should be designed as if it were powered by batteries, and one should learn from mobile devices". The guiding principle for new development could be: "Every circuit should be designed as if it were powered by batteries, and one should learn from mobile devices".
 +
  
 ==== Measurement uncertainty ==== ==== Measurement uncertainty ====
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 ===== See also ===== ===== See also =====
 +
 +[[phi_publications:nr.59_building_automation_for_energy-efficient_buildings|Building automation for energy-efficient buildings]]
  
 More detailed information can be found [[https://database.passivehouse.com/de/download/product_page/Protokollband59|Protokollband 59 ]] (German) More detailed information can be found [[https://database.passivehouse.com/de/download/product_page/Protokollband59|Protokollband 59 ]] (German)
  
  
planning/non-residential_passive_house_buildings/building_automation.1699889208.txt.gz · Last modified: by wolfgang.hasper@passiv.de