Passipedia EN

User Tools

Site Tools

You are here: Passipedia - The Passive House Resource » Passive House Institute publications » pb_41 » PB 41: Planning tools for the summer situation in non-residential buildings
phi_publications:pb_41:planning_tools_for_the_summer_situation_in_non-residential_buildings

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
phi_publications:pb_41:planning_tools_for_the_summer_situation_in_non-residential_buildings [2018/04/20 13:28] – [2.2 Useful cooling demand] kdreimanephi_publications:pb_41:planning_tools_for_the_summer_situation_in_non-residential_buildings [2019/09/09 13:24] (current) – [3.4 Use for critical rooms] cblagojevic
Line 6: Line 6:
 The summer behaviour of non-residential buildings often plays an important role when planning these, because the boundary conditions that are relevant for the summer can differ significantly from those in residential buildings. Sometimes concentrated internal heat loads may occur during certain times, for example in classrooms or conference rooms. Occasionally, due to higher occupancy density and greater technologisation, these internal loads may be considerably higher than those in residential buildings. Added to this is the tendency to use large glazing areas for utilising daylight and also for aesthetic reasons. These result in accordingly higher solar gains. In some circumstances, a dress code may also apply in non-residential buildings which, in case of moderately high temperatures, may lead to exceeding of the comfortable range. The summer behaviour of non-residential buildings often plays an important role when planning these, because the boundary conditions that are relevant for the summer can differ significantly from those in residential buildings. Sometimes concentrated internal heat loads may occur during certain times, for example in classrooms or conference rooms. Occasionally, due to higher occupancy density and greater technologisation, these internal loads may be considerably higher than those in residential buildings. Added to this is the tendency to use large glazing areas for utilising daylight and also for aesthetic reasons. These result in accordingly higher solar gains. In some circumstances, a dress code may also apply in non-residential buildings which, in case of moderately high temperatures, may lead to exceeding of the comfortable range.
    
-Questions, such as whether thermal comfort in summer is adequate even without active cooling, or how high the energy demand for space cooling is, and how high the output of the cooling system must be, are therefore particularly relevant when planning non-residential buildings.  In principle, it is always possible to carry out a dynamic thermal building simulation for assessing the summer conditions. With careful data acquisition and application of suitable models, this can predict the thermal conditions inside the building with a high degree of accuracy. However, not all building simulation programmes depict the relevant heat transfer processes sufficiently accurately; usually the performed calculations are barely verifiable and the effort for a substantiated and meaningful simulation is high. For example, in order toobtain results that justify the effort for a simulation, it is generally also necessary to include the adjacent zones besides the thermal zones that are of actual interest.  (See also Section 3.4).+Questions, such as whether thermal comfort in summer is adequate even without active cooling, or how high the energy demand for space cooling is, and how high the output of the cooling system must be, are therefore particularly relevant when planning non-residential buildings.  In principle, it is always possible to carry out a dynamic thermal building simulation for assessing the summer conditions. With careful data acquisition and application of suitable models, this can predict the thermal conditions inside the building with a high degree of accuracy. However, not all building simulation programmes depict the relevant heat transfer processes sufficiently accurately; usually the performed calculations are barely verifiable and the effort for a substantiated and meaningful simulation is high. For example, in order to obtain results that justify the effort for a simulation, it is generally also necessary to include the adjacent zones besides the thermal zones that are of actual interest.  (See also Section 3.4).
  
 The following article will therefore deal with the validity of simplified algorithms as already implemented in the Passive House Planning Package [PHPP] for non-residential buildings currently. It is obvious that there are limitations for such simplified methods; it is essential to be aware of the limits of this application. The focus of this article is on usage as offices or seminar rooms since, for one thing, this type of usage is very common, and for another, the differences from residential buildings as mentioned above are already relatively distinct.  The following article will therefore deal with the validity of simplified algorithms as already implemented in the Passive House Planning Package [PHPP] for non-residential buildings currently. It is obvious that there are limitations for such simplified methods; it is essential to be aware of the limits of this application. The focus of this article is on usage as offices or seminar rooms since, for one thing, this type of usage is very common, and for another, the differences from residential buildings as mentioned above are already relatively distinct. 
Line 12: Line 12:
 The article will first consider the case of active cooling. Of central interest here are the calculation of the annual useful energy demand for space cooling (hereafter referred to as useful cooling), and the cooling load. In the second part, calculation of the frequency of overheating, i.e. the number of hours in a year where the indoor temperature exceeds 25°C in passively cooled buildings, will be examined in more detail for non-residential buildings. The article will first consider the case of active cooling. Of central interest here are the calculation of the annual useful energy demand for space cooling (hereafter referred to as useful cooling), and the cooling load. In the second part, calculation of the frequency of overheating, i.e. the number of hours in a year where the indoor temperature exceeds 25°C in passively cooled buildings, will be examined in more detail for non-residential buildings.
  
-Verification of the simplified algorithms in the PHPP will take place based on the simulations using the dynamic thermal building simulation software DYNBIL, which has been validated for residential and office use based on measurements in inhabited buildings. The algorithms in the DYNBIL programme are so close to physical principles that we consider the results to be valid for other types of usage.+Verification of the simplified algorithms in the PHPP will take place based on the simulations using the dynamic thermal building simulation software DYNBIL, which has been validated for residential and office use based on measurements in inhabited buildings. The algorithms in the DYNBIL program are so close to physical principles that we consider the results to be valid for other types of usage.
  
 The calculations will take place using the same simulation model which was used for the article on concrete core temperature control by Wolfgang Hasper in this Protocol Volume. The room being studied can be situated in the centre of one side of the building or at the corner; accordingly it has windows on one or two sides, either with a moderate window ratio of 40% of the respective facade, or as full glazing. Different levels of insulation can also be considered, based on the Passive House standard or the currently valid EnEV standard for new buildings. Important note: the windows in the following examined cases are without exterior shading, so that high solar loads can also be depicted. In part, a variant without windows will be examined in order to allow depiction of the behaviour of buildings with effective exterior shading attachments, e.g. venetian blinds in front of triple low-e glazing. The calculations will take place using the same simulation model which was used for the article on concrete core temperature control by Wolfgang Hasper in this Protocol Volume. The room being studied can be situated in the centre of one side of the building or at the corner; accordingly it has windows on one or two sides, either with a moderate window ratio of 40% of the respective facade, or as full glazing. Different levels of insulation can also be considered, based on the Passive House standard or the currently valid EnEV standard for new buildings. Important note: the windows in the following examined cases are without exterior shading, so that high solar loads can also be depicted. In part, a variant without windows will be examined in order to allow depiction of the behaviour of buildings with effective exterior shading attachments, e.g. venetian blinds in front of triple low-e glazing.
Line 20: Line 20:
 ==== 2.1 Prologue: heating ==== ==== 2.1 Prologue: heating ====
  
-[{{:picprivate:f1.png?nolink&600 |**Figure 1: The principle of the energy balance method for heating: Indoor temperatures in a non-residential building for a week in January** \\ //Heizleistung=heating power, nicht nutzbare Gewinne=non-usable gains, Raumtemperatur=indoor temperature, Heizung=heating//}}]+[{{:picopen:41_11.jpg?nolink&600 |**Figure 1: The principle of the energy balance method for heating: Indoor temperatures in a non-residential building for a week in January** }}]
 Dynamic simulations calculate the thermal conditions in the building in time steps which are usually much less than one hour. Heat transfer processes in building components and the room are shown in detail. In contrast with this, there are energy balancing methods such as the annual and monthly method used in the PHPP or the  DIN V 18599, which  calculates the heating balance  by means of a specified balance boundary over longer periods of time using the law of conservation of energy. Energy balancing methods have significant advantages in terms of application, computation time and interpretability, whereby the results for the heating demand of typical residential and non-residential buildings correspond very well with the dynamic simulation.  Dynamic simulations calculate the thermal conditions in the building in time steps which are usually much less than one hour. Heat transfer processes in building components and the room are shown in detail. In contrast with this, there are energy balancing methods such as the annual and monthly method used in the PHPP or the  DIN V 18599, which  calculates the heating balance  by means of a specified balance boundary over longer periods of time using the law of conservation of energy. Energy balancing methods have significant advantages in terms of application, computation time and interpretability, whereby the results for the heating demand of typical residential and non-residential buildings correspond very well with the dynamic simulation. 
  
Line 28: Line 28:
  
  
-|{{:picprivate:f2.png?nolink&600}} | {{:picprivate:f2_1.png?nolink&600}} |+[{{:picopen:41_12.jpg?nolink&600 | **Figure 2: Example of utilisation factor and heat gains plotted against the gains/losses ratio. The theoretical upper limit for the utilisation limit is also shown in the figure on the left. The gradients differ slightly depending on the time constants of the buildings.** }}]
  
-|**Figure 2: Example of utilisation factor and heat gains plotted against the gains/losses ratio. The theoretical upper limit for the utilisation limit is also shown in the figure on the left. The gradients differ slightly depending on the time constants of the buildings.** \\ //Nutzungsgrad Wärmegewinne=utilisation factor for heat gains, Gewinn-Verlust-Verhaltnis=gain/loss ratio, Wärmegewinne [Verlust]=heat gains [loss], interne & solare Gewinne=internal and solar gains, davon nutzbar=usable internal and solar gains//| +The monthly method in the PHPP uses the utilisation factors in accordance with [EN 13790]. Experience with this calculation method for residential buildings has been excellent compared with the dynamic building simulation (for example, see [Feist 1998]), and it also proved successful for inhabited buildings as well as in the direct probation of inhabited buildings.
- +
-The monthly method in the PHPP uses the utilisation factors in accordance with [EN 13790]. Experience with this calculation method for residential buildings has been excellent compared with the dynamic building simulation (for example, see [Feist 1998]), and it also proved successful for inhabited buildings als auch in der direkten Bewährung bei bewohnten Gebäuden ausgezeichnet.+
  
 Two examples provide more information regarding the scope of application of this method. Figure 3 shows the calculated heating demand for the central room of the simulation model with a window on one side and insulation to the EnEV standard, calculated with consistent indoor conditions with various levels of internal gains and window area ratios. The calculation was carried out using the PHPP as well as the dynamic model in DYNBIL as the comparison standard. For the case without windows, it can be seen that there is excellent correlation between the simulation and energy balance method for all values for internal heat gains. The gradients only diverge noticeably in the case of larger window areas and extra high internal heat gains.  Two examples provide more information regarding the scope of application of this method. Figure 3 shows the calculated heating demand for the central room of the simulation model with a window on one side and insulation to the EnEV standard, calculated with consistent indoor conditions with various levels of internal gains and window area ratios. The calculation was carried out using the PHPP as well as the dynamic model in DYNBIL as the comparison standard. For the case without windows, it can be seen that there is excellent correlation between the simulation and energy balance method for all values for internal heat gains. The gradients only diverge noticeably in the case of larger window areas and extra high internal heat gains. 
  
-[{{:picprivate:f3.png?nolink&600 |**Figure 3: Comparison of the calculated heating demand for the centre office based on the EnEV standard, according to the simulation and PHPP.** \\ //HWB (Heizwärmebedarf)=HD (heating demand), Transparenz=transparency, Interne Wärmegewinne=internal heat gains//}}]+[{{:picopen:41_13.jpg?nolink&600 |**Figure 3: Comparison of the calculated heating demand for the centre office based on the EnEV standard, according to the simulation and PHPP.**}}]
  
 Principally, the results are similar in the second case with the Passive House corner room with windows in both exterior walls (Figure 4). Both calculation methods correlate very well if there are no windows areas or if window areas are moderate. The results no longer correlate well only in the case with full glazing; the simulation yields significantly higher heating demand values. The difference is greatest for low internal heat gains where it is just 5 kWh/(m²a). This variation is certainly due in part to the fact that the solar gains are ca. 125 kWh/(m²a) with this configuration, of which  13 % are reflected back in the simulation model, while this type of geometrical effect is not specifically taken into account in the PHPP. The difference in the solar supply alone is thus already greater than 15 kWh/(m²a). Principally, the results are similar in the second case with the Passive House corner room with windows in both exterior walls (Figure 4). Both calculation methods correlate very well if there are no windows areas or if window areas are moderate. The results no longer correlate well only in the case with full glazing; the simulation yields significantly higher heating demand values. The difference is greatest for low internal heat gains where it is just 5 kWh/(m²a). This variation is certainly due in part to the fact that the solar gains are ca. 125 kWh/(m²a) with this configuration, of which  13 % are reflected back in the simulation model, while this type of geometrical effect is not specifically taken into account in the PHPP. The difference in the solar supply alone is thus already greater than 15 kWh/(m²a).
Line 46: Line 44:
 Altogether, in the energy balance method, the utilisation factor appears to have been calculated a little too low with constantly free heat (i.e. dominating constant IHG), and a little too high with temporally concentrated free heat. Thus, in typical cases both influences balance each other out and the heating demand according to the PHPP correlates with the simulation. Altogether, in the energy balance method, the utilisation factor appears to have been calculated a little too low with constantly free heat (i.e. dominating constant IHG), and a little too high with temporally concentrated free heat. Thus, in typical cases both influences balance each other out and the heating demand according to the PHPP correlates with the simulation.
  
-|{{:picprivate:f4.png?nolink&600}} | {{:picprivate:f5.png?nolink&600}}| +---- 
-|**Figure 4: Comparison of the calculated heating demand for the corner office in the Passive House standard according to the simulation and the PHPP** \\ //Passivhaus, Ecke....=Passive House, corner, IHG/ventilation for office, constant set temperature, dito auf 25°C begrenzt= ditto limited to 25°C, HWB (Heizwärmebedarf)=HD (heating demand), Transparenz=transparency, Interne Wärmegewinne=internal heat gains// | **Figure 5: Temperature curve and heating output for the fully glazed situation with low internal heat gains from Figure 4. This figure shows the standard case where the indoor temperatures may increase without limitation, and the case where  the indoor temperature is limited to 25°C.** \\ //Temperatur=temperature, Heizleistung=heating output, dito auf 25°C begrenzt= ditto limited to 25°C.// |+ 
 +|{{:picopen:41_010.jpg?nolink&600}}|{{:picopen:41_14.jpg?nolink&600}}| 
 +|**Figure 4: Comparison of the calculated heating demand for the corner office in the Passive House standard according to the simulation and the PHPP**  | **Figure 5: Temperature curve and heating output for the fully glazed situation with low internal heat gains from Figure 4. This figure shows the standard case where the indoor temperatures may increase without limitation, and the case where  the indoor temperature is limited to 25°C.** |
  
  
  
 ====2.2 Useful cooling demand ==== ====2.2 Useful cooling demand ====
-[{{:picprivate:f6.png?nolink&600|**Figure 6: The principle of the energy balance method for the cooling demand: Indoor temperature and cooling output in a non-residential building without shading for a period in April.** //Kühlleistung=cooling output, Operativ Temperatur=operative temperature, Raumtemperatur=indoor temperature, Solltemperatur=setpoint temperature//}}]+[{{:picopen:41_15.jpg?nolink&600|**Figure 6: The principle of the energy balance method for the cooling demand: Indoor temperature and cooling output in a non-residential building without shading for a period in April.**}}]
 The principle of energy balancing using a utilisation factor works not only for heating but also for cooling. In the Central European climate, periods requiring cooling, as well as periods without a cooling demand, arise on many days during the summer. Figure 6 illustrates this situation.  The principle of energy balancing using a utilisation factor works not only for heating but also for cooling. In the Central European climate, periods requiring cooling, as well as periods without a cooling demand, arise on many days during the summer. Figure 6 illustrates this situation. 
  
Line 65: Line 65:
 ---- ----
  
-| {{:picprivate:f7.png?nolink&600}} | {{ :picprivate:f8.png?nolink&600}} | +|{{:picprivate:41_16.jpg?nolink&600}} |{{ :picprivate:41_17.jpg?nolink&600}} | 
-|**Figure 7: Comparison of the calculated useful cooling demand for a centre office to the EnEV standard, according to the simulation and the PHPP** \\ //Nutzkältebedarf=useful cooling demand, Interne Wärmegewinne=internal heat gains, KB=cooling demand, Transparenz=transparency, EnEV,mitte...=EnEV,centre, constant IHG/ventilation/set temperature // | **Figure 8: Comparison of the calculated useful cooling demand for a corner office to the Passive House standard according to the simulation  and the PHPP** \\ //Nutzkältebedarf=useful cooling demand, Interne Wärmegewinne=internal heat gains, KB=cooling demand, Transparenz=transparency, Passivhaus, Ecke...= Passive House corner, IHG/office ventilation, constant set temperature// |+|**Figure 7: Comparison of the calculated useful cooling demand for a centre office to the EnEV standard, according to the simulation and the PHPP**  | **Figure 8: Comparison of the calculated useful cooling demand for a corner office to the Passive House standard according to the simulation  and the PHPP** |
  
  
Line 75: Line 75:
 Based on Figure 9, utilisation as a seminar room was therefore considered in addition. Internal heat loads of 25 W/m² prevail from Monday till Friday afternoon, during the highest outdoor temperatures, which equates to average internal loads of 3 W/m². A temperature requirement arises only during these times; outside of the usage periods, the temperature in the room can be set freely. The window areas are reasonably dimensioned; active cooling is augmented through intensive ventilation with an air change rate of 5 h<sup>-1</sup> during the summer. Based on Figure 9, utilisation as a seminar room was therefore considered in addition. Internal heat loads of 25 W/m² prevail from Monday till Friday afternoon, during the highest outdoor temperatures, which equates to average internal loads of 3 W/m². A temperature requirement arises only during these times; outside of the usage periods, the temperature in the room can be set freely. The window areas are reasonably dimensioned; active cooling is augmented through intensive ventilation with an air change rate of 5 h<sup>-1</sup> during the summer.
  
-|{{:picprivate:f9.png?nolink&450}} | {{:picprivate:f10.png?nolink&450}} | +|{{:picprivate:41_18.jpg?nolink&600}} | {{:picprivate:41_19.jpg?nolink&600}} | 
-| **Figure 9: Temperature curve for seminar room usage with intensive nighttime ventilation and respective cooling output** \\ //Temperatur=temperature, Kühlleistung=cooling output, Mo-Fr von 14 bis 18 Uhr=Mon-Fri from 14:00 till 18:00 p.m., Grafik=Illustration, Passivhaus, Mitte....=Passive House, centre, 40% transparent, 3W/m², IHG/ventilation/set temperature seminar room Operation// | **Figure 10: Comparison of the calculated useful cooling demand for a centre office to the Passive House standard with seminar room use according to the simulation  and the PHPP** \\ //Nutzkältebedarf= useful cooling demand, Max. Luftwechsel Sommer=maximum air change rate in summer, Passivhaus, Mitte....=Passive House, centre, 40% transparent, IHG/ventilation/set temperature seminar room Operation// |+| **Figure 9: Temperature curve for seminar room usage with intensive nighttime ventilation and respective cooling output** | **Figure 10: Comparison of the calculated useful cooling demand for a centre office to the Passive House standard with seminar room use according to the simulation  and the PHPP** |
  
 As can be seen in Figure 10, the energy balance method functions perfectly well even in this situation. This is astounding, given the fact that information regarding temporal distribution of the internal loads is not available in the PHPP at all.   As can be seen in Figure 10, the energy balance method functions perfectly well even in this situation. This is astounding, given the fact that information regarding temporal distribution of the internal loads is not available in the PHPP at all.  
Line 97: Line 97:
 According to these results, the cooling load method of the PHPP is suitable for buildings with minimised loads, i.e. a good level of solar protection and internal loads that are either small or uniformly distributed in time. In these cases it provides enough reliability to compensate for some of the temperature fluctuations occurring during the course of the day. If loads are so high that daily buffering is no longer possible, then a method with higher time resolution will have to be used. According to these results, the cooling load method of the PHPP is suitable for buildings with minimised loads, i.e. a good level of solar protection and internal loads that are either small or uniformly distributed in time. In these cases it provides enough reliability to compensate for some of the temperature fluctuations occurring during the course of the day. If loads are so high that daily buffering is no longer possible, then a method with higher time resolution will have to be used.
  
-|{{:picprivate:f11.png?nolink&600 }} | {{:picprivate:f12.png?nolink&600}} | +|{{:picprivate:41_20.jpg?nolink&600 }} | {{:picprivate:41_21.jpg?nolink&600}} | 
-|**Figure 11: Cooling load plotted against the internal heat load according to different calculation methods - without windows** \\ // EnEV, Mitte...=EnEV, centre, 0% transparency, IHG/ventilation/set temperature constant, Kühllast=cooling load, Interne Wärmegewinne=internal heat gains, Stundenmittel=hourly mean, Tagesmittel=daily mean // | **Figure 12: Cooling load plotted against the internal heat load according to different calculation methods - ribbon window facade** \\ // EnEV, Mitte...=EnEV, centre, 40% transparency, IHG/ventilation/set temperature constant, Kühllast=cooling load, Interne Wärmegewinne=internal heat gains, Stundenmittel=hourly mean, Tagesmittel=daily mean// |+|**Figure 11: Cooling load plotted against the internal heat load according to different calculation methods - without windows** | **Figure 12: Cooling load plotted against the internal heat load according to different calculation methods - ribbon window facade**  |
  
-|{{:picprivate:f13.png?nolink&1300}} | {{:picprivate:f14.png?nolink&450}} | +|{{ :picprivate:41_22.jpg?nolink&800}} | {{ :picprivate:41_23.jpg?nolink&600}} | 
-| **Figure 13: Cooling load plotted against the internal heat load according to different calculation methods - fully glazed facade**\\ //EnEV, Mitte...=EnEV, centre, 100% transparency, IHG/ventilation/set temperature constant, Kühllast=cooling load, Interne Wärmegewinne=internal heat gains, Stundenmittel=hourly mean, Tagesmittel=daily mean// | **Figure 14: Cooling load plotted against the internal heat load according to different calculation methods. Here the daily mean values from Figures 11 to 13 are summarised supplemented with the results of the simulation for the extreme summer** \\ //EnEV, Mitte...=EnEV, centre, IHG/ventilation/set temperature constant, Kühllast=cooling load, Interne Wärmegewinne=internal heat gains, Stundenmittel=hourly mean, Tagesmittel=daily mean, Extremsommer=extreme summer// |+| **Figure 13: Cooling load plotted against the internal heat load according to different calculation methods - fully glazed facade**| **Figure 14: Cooling load plotted against the internal heat load according to different calculation methods. Here the daily mean values from Figures 11 to 13 are summarised supplemented with the results of the simulation for the extreme summer** |
  
 =====3 Frequency of overheating ===== =====3 Frequency of overheating =====
Line 120: Line 120:
 Since temperature fluctuations are  relevant for calculation of the frequency of overheating, this inevitably entails the use of a dynamic calculation method. In order to avoid a complicated dynamic simulation based on hourly data, a greatly simplified dynamic method is used in the PHPP. Figure 15 illustrates this principle in comparison with a dynamic simulation for the same underlying test reference year. The course of the indoor temperature curve is determined under constant monthly boundary conditions using a 1-output model. There is an exponential indoor temperature curve for each month, the average value of which can be calculated using analytical methods. If the indoor temperature is less than the heating setpoint temperature at the end of the month, the following month starts with the heating setpoint temperature again.  Since temperature fluctuations are  relevant for calculation of the frequency of overheating, this inevitably entails the use of a dynamic calculation method. In order to avoid a complicated dynamic simulation based on hourly data, a greatly simplified dynamic method is used in the PHPP. Figure 15 illustrates this principle in comparison with a dynamic simulation for the same underlying test reference year. The course of the indoor temperature curve is determined under constant monthly boundary conditions using a 1-output model. There is an exponential indoor temperature curve for each month, the average value of which can be calculated using analytical methods. If the indoor temperature is less than the heating setpoint temperature at the end of the month, the following month starts with the heating setpoint temperature again. 
  
-[{{:picprivate:f15.png?nolink&600 |**Figure 15: Calculation of the frequency of overheating in the PHPP. The constant monthly values are used in the PHPP, the hourly values are used in the dynamic simulation.** \\ //Außentemperatur=outdoor temperature, Raumtemperatur=indoor temperature, Mitteltemperatur=average temperature, Grafik=Illustration//}}]+[{{ :picprivate:41_24.jpg?nolink&600 |**Figure 15: Calculation of the frequency of overheating in the PHPP. The constant monthly values are used in the PHPP, the hourly values are used in the dynamic simulation.** }}]
  
 In order to be able to show the influence of individual hot days as well, and to obtain meaningful results for small overheating frequency values, the month of July is additionally divided into several parts: the cooling load day at the end of the month, the four preceding days with slightly lower temperatures and radiation values, another twelve preceding days with lower temperatures and radiation values once more, and the then the rest of the month. In the process, the month is divided in such a way that the monthly average values for the outdoor temperature and solar incidence for July remain unchanged. The average values for the indoor temperature are also determined in the same way for these shorter periods.  In order to be able to show the influence of individual hot days as well, and to obtain meaningful results for small overheating frequency values, the month of July is additionally divided into several parts: the cooling load day at the end of the month, the four preceding days with slightly lower temperatures and radiation values, another twelve preceding days with lower temperatures and radiation values once more, and the then the rest of the month. In the process, the month is divided in such a way that the monthly average values for the outdoor temperature and solar incidence for July remain unchanged. The average values for the indoor temperature are also determined in the same way for these shorter periods. 
Line 138: Line 138:
 The correlation of the simulation and simplified PHPP calculation for use in non-residential buildings with moderate and high internal loads of 3 or 9 W/m² are shown in Figures 16 and 17. A ribbon window facade on one side was assumed in each case, since passive cooling is not possible for fully glazed buildings without any exterior shading in any case. The correlation of the simulation and simplified PHPP calculation for use in non-residential buildings with moderate and high internal loads of 3 or 9 W/m² are shown in Figures 16 and 17. A ribbon window facade on one side was assumed in each case, since passive cooling is not possible for fully glazed buildings without any exterior shading in any case.
  
-As might be expected, the frequency of overheating depends greatly on the air change rate of summer ventilation. Differences result mainly with low air change rates and high overheating frequencies in the case of moderate internal loads of 3 W/m². Here the exact value of the overheating frequency results from the average monthly values of the boundary conditions, so that a certain level of inaccuracy is unavoidable. Highly precise results are also unnecessary as it is enough to have certaincy of direction and the knowledge that the building is extremely uncomfortable under these conditions. +As might be expected, the frequency of overheating depends greatly on the air change rate of summer ventilation. Differences result mainly with low air change rates and high overheating frequencies in the case of moderate internal loads of 3 W/m². Here the exact value of the overheating frequency results from the average monthly values of the boundary conditions, so that a certain level of inaccuracy is unavoidable. Highly precise results are also unnecessary as it is enough to have certainty of direction and the knowledge that the building is extremely uncomfortable under these conditions. 
  
 There is a similar tendency for high loads with 9 W/m². However, for air change rates higher than 3 h<sup>-1</sup>, the summer ventilation algorithm of the PHPP provides values that are too pessimistic; while the frequency of overheating with a five-fold air change rate is already within the acceptable range according to the simulation, this is not the case with the PHPP. This difference is due to the method used for calculating the removal of heat through summer ventilation. There are still possibilities for refining the calculation method, but the PHPP algorithm is at least on the safe side.  There is a similar tendency for high loads with 9 W/m². However, for air change rates higher than 3 h<sup>-1</sup>, the summer ventilation algorithm of the PHPP provides values that are too pessimistic; while the frequency of overheating with a five-fold air change rate is already within the acceptable range according to the simulation, this is not the case with the PHPP. This difference is due to the method used for calculating the removal of heat through summer ventilation. There are still possibilities for refining the calculation method, but the PHPP algorithm is at least on the safe side. 
  
-|{{:picprivate:f16.png?nolink&600}} | {{:picprivate:f17.png?nolink&600}} | +|{{ :picprivate:41_25.jpg?nolink&600 |}} | {{ :picprivate:41_017.jpg?nolink&600 |}} | 
-|**Figure 16: Example with frequency of overheating plotted against air change rate in summer for low internal heat loads** \\ //Baustandard Passivhaus....=Passive House construction standard 3 W/m², constant, centre office, 40% windows, Anteil Stunden über 25°C=Percentage of hours over 25°C, max. Sommerluftwechsel=maximum air change rate in summer// | **Figure 17: Example with frequency of overheating plotted against air change rate in summer for high internal heat loads** \\ // Baustandard Passivhaus....=Passive House construction standard 9 W/m², constant, centre office, 40% windows, Anteil Stunden über 25°C=Percentage of hours over 25°C, max. Sommerluftwechsel=maximum air change rate in summer // |+|**Figure 16: Example with frequency of overheating plotted against air change rate in summer for low internal heat loads**  | **Figure 17: Example with frequency of overheating plotted against air change rate in summer for high internal heat loads**  |
  
  
 ==== 3.2 Conversion to usage period? ==== ==== 3.2 Conversion to usage period? ====
-[{{:picprivate:f18.png?nolink&600 |**Figure 18: Example with frequency of overheating plotted against air change rate in summer for a fully glazed corner office with moderate internal heat loads** \\ //Nutzungszeit=usage period, Operative temperature=operative temperature//}}]+[{{:picprivate:41_26.jpg?nolink&600 |**Figure 18: Example with frequency of overheating plotted against air change rate in summer for a fully glazed corner office with moderate internal heat loads** }}]
  
 In non-residential buildings, the question of whether all hours with overheating fall within the usage period arises on account of the intermittent usage. If that was the case, then the frequency of overheating  determined in the PHPP can (and must) be converted to that occurring during the usage - as a meaningful measure of thermal comfort in summer - using the factor tYear/tUse. In non-residential buildings, the question of whether all hours with overheating fall within the usage period arises on account of the intermittent usage. If that was the case, then the frequency of overheating  determined in the PHPP can (and must) be converted to that occurring during the usage - as a meaningful measure of thermal comfort in summer - using the factor tYear/tUse.
Line 159: Line 159:
 Based on the entire year and the usage period, the overheating frequencies can differ considerably depending on the air change rates which are possible in summer. Conversion with the ratio of usage period to the entire year would also give pessimistic results, but the difference is no longer as great. The reason for this can be seen in the upper chart in Figure 19, where the temperature curve for high summer air change rate is shown. The excessive temperatures actually occur almost exclusively during the usage period.   Based on the entire year and the usage period, the overheating frequencies can differ considerably depending on the air change rates which are possible in summer. Conversion with the ratio of usage period to the entire year would also give pessimistic results, but the difference is no longer as great. The reason for this can be seen in the upper chart in Figure 19, where the temperature curve for high summer air change rate is shown. The excessive temperatures actually occur almost exclusively during the usage period.  
  
-|{{ :picprivate:f19.png?nolink&600 }} | {{ :picprivate:f19_1.png?nolink&600 }}|+|{{ :picprivate:41_27.jpg?nolink&600 |}} | {{ :picprivate:41_28.jpg?nolink&600 |}}|
  
 |**Figure 19: Example with frequency of overheating plotted against air change rate in summer for high internal heat loads and seminar room usage. The simulation results are also shown with reference to the operating times, the PHPP results were converted using the factor tYear/tUse |**Figure 19: Example with frequency of overheating plotted against air change rate in summer for high internal heat loads and seminar room usage. The simulation results are also shown with reference to the operating times, the PHPP results were converted using the factor tYear/tUse
-The chart above shows the temperature curve in summer and the usage period for high air change rates in May.** \\ //Nutzungszeit=usage period, Operative temperature=operative temperature, Anteil...=Percentage of hours over 25°C, Max. Sommerluftwechsel=maximum air change rate in summer//|+The chart above shows the temperature curve in summer and the usage period for high air change rates in May.** |
  
 ==== 3.3 Accuracy limits for calculating the frequency of overheating ==== ==== 3.3 Accuracy limits for calculating the frequency of overheating ====
Line 170: Line 170:
 These examples demonstrate that it is generally not possible to make statements regarding thermal comfort in summer which are more precise than those derived from the categories in Table 1. It is difficult to predict even the summer air change rate, because according to the system, it depends more or less on user behaviour. The outside temperatures and wind speeds which are influenced by the microclimate also affect the removal of heat through night-time ventilation. The year-to-year fluctuations in weather are not subject to any influence in any case. These examples demonstrate that it is generally not possible to make statements regarding thermal comfort in summer which are more precise than those derived from the categories in Table 1. It is difficult to predict even the summer air change rate, because according to the system, it depends more or less on user behaviour. The outside temperatures and wind speeds which are influenced by the microclimate also affect the removal of heat through night-time ventilation. The year-to-year fluctuations in weather are not subject to any influence in any case.
  
-|{{:picprivate:f20.png?nolink&800}} |**40 %, north, 3 W/m² constant, nSumm = 1.8 h<sup>-1</sup>: frequency of overheating 1%, maximum temperature 26°C** | +|{{ :picprivate:41_291.jpg?nolink&800}} |**40 %, north, 3 W/m² constant, nSumm = 1.8 h<sup>-1</sup>: frequency of overheating 1%, maximum temperature 26°C** | 
-|{{:picprivate:f20_1.png?nolink&800}}  |**40 %, north, 3 W/m² constant, nSumm = 0.6 h<sup>-1</sup>:frequency of overheating 16%, maximum temperature 29°C** | +|{{ :picprivate:41_292.jpg?nolink&800}}  |**40 %, north, 3 W/m² constant, nSumm = 0.6 h<sup>-1</sup>:frequency of overheating 16%, maximum temperature 29°C** | 
-|{{:picprivate:f20_2.png?nolink&800}}|**40 %, north, 3 W/m² constant, nSumm = 1.8 h<sup>-1</sup>, extreme summer: frequency of overheating 14%, maximum temperature 31 °C**|+|{{ :picprivate:41_293.jpg?nolink&800}} |**40 %, north, 3 W/m² constant, nSumm = 1.8 h<sup>-1</sup>, extreme summer: frequency of overheating 14%, maximum temperature 31 °C**|
  
 |**Figure 20: Temperature curve in an example room according to weather and air change rate**| |**Figure 20: Temperature curve in an example room according to weather and air change rate**|
Line 186: Line 186:
 In the opposite case, individually considering a room is just as inadequate (Figure 22). Taken alone, summer thermal comfort in the room under consideration is excellent. However, if the adjacent rooms are intensely uncomfortable on account of full glazing and high internal heat loads, then this will also affect the centre room being examined; the frequency of overheating is now 13%. In the opposite case, individually considering a room is just as inadequate (Figure 22). Taken alone, summer thermal comfort in the room under consideration is excellent. However, if the adjacent rooms are intensely uncomfortable on account of full glazing and high internal heat loads, then this will also affect the centre room being examined; the frequency of overheating is now 13%.
  
-|{{:picprivate:f21.png?nolink&700}}| **40 %, north, 3 W/m² constant, nSumm = 1.8 h<sup>-1</sup>, extreme summer: frequency of overheating 14%, maximum temperature 30 °C** \\ // Außentemperatur=outdoor temperature, Raum=room, Tagesmittel=daily mean, Operative Temperatur=operative temperature //| +|{{:picprivate:41_30_1.jpg?nolink&700}}| **40 %, north, 3 W/m² constant, nSumm = 1.8 h<sup>-1</sup>, extreme summer: frequency of overheating 14%, maximum temperature 30 °C** | 
-|{{ :picprivate:f21_1.png?nolink&700}} | **ditto, ground floor and top floor without windows and with 1 W/m²: +|{{:picprivate:41_30_2.jpg?nolink&700}} | **ditto, ground floor and top floor without windows and with 1 W/m²: 
-frequency of overheating 4%, maximum temperature 28 °C** \\ // Außentemperatur=outdoor temperature, Raum=room, EG=ground floor, DG=top floor,  Operative Temperatur=operative temperature// |+frequency of overheating 4%, maximum temperature 28 °C**|
  
 |**Figure 21: Temperature curve as a function of adjacent rooms, part 1**| |**Figure 21: Temperature curve as a function of adjacent rooms, part 1**|
  
  
-|{{:picprivate:f22.png?nolink&900}}| **40 %, north, 3 W/m² constant, nSumm = 1.8 h-1:frequency of overheating 1%, maximum temperature 26 °C** \\ // Außentemperatur=outdoor temperature, Raum=room, EG=ground floor, DG=top floor, Tagesmittel=daily mean,  Operative Temperatur=operative temperature //  | +|{{:picprivate:41_311.jpg?nolink&900}}| **40 %, north, 3 W/m² constant, nSumm = 1.8 h-1:frequency of overheating 1%, maximum temperature 26 °C** | 
-|{{:picprivate:f22_1.png?nolink&900}}| **ditto, ground floor and top floor, fully glazed with 9 W/m²: frequency of overheating 13%, maximum temperature 30 °C**|+|{{:picprivate:41_312.jpg?nolink&900}}| **ditto, ground floor and top floor, fully glazed with 9 W/m²: frequency of overheating 13%, maximum temperature 30 °C**|
  
 |**Figure 22: Temperature curve as a function of adjacent rooms, part 2**| |**Figure 22: Temperature curve as a function of adjacent rooms, part 2**|
phi_publications/pb_41/planning_tools_for_the_summer_situation_in_non-residential_buildings.1524223732.txt.gz · Last modified: 2018/04/20 13:28 by kdreimane