Passipedia EN

User Tools

Site Tools

You are here: Passipedia - The Passive House Resource » Planning and Construction » Non-residential Passive House buildings » Building automation
planning:non-residential_passive_house_buildings:building_automation

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
planning:non-residential_passive_house_buildings:building_automation [2023/12/21 11:41] – [Potentials of building automation] wolfgang.hasper@passiv.deplanning:non-residential_passive_house_buildings:building_automation [2024/06/06 13:05] (current) – yaling.hsiao@passiv.de
Line 51: Line 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. 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.
Line 75: Line 75:
 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:
Line 85: Line 89:
 |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)|
Line 242: Line 246:
 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.
  
  
Line 433: Line 437:
  
 ===== 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.1703155269.txt.gz · Last modified: by wolfgang.hasper@passiv.de