PsyChart error - Grasshopper2024-03-28T21:37:26Zhttps://www.grasshopper3d.com/forum/topics/psychart-error?groupUrl=ladybug&commentId=2985220%3AComment%3A1808863&groupId=2985220%3AGroup%3A658987&feed=yes&xn_auth=noAbraham,
That is a nice paper…tag:www.grasshopper3d.com,2017-09-10:2985220:Comment:18114672017-09-10T20:45:37.432ZChris Mackeyhttps://www.grasshopper3d.com/profile/ChrisMackey
Abraham,<br />
That is a nice paper on thermal mass and the results make sense to me. The effect of thermal mass on the peak temperature is usually huge and is overlooked by simple psych chart studies like this one that focus on the % time that you can use a certain strategy fall inside a comfort polygon (rather than how much more comfortable the worst-case scenario is).<br />
<br />
Your rules of thumb for solarHeatCapacity look good and the only thing that I would clarify when you use them is that they assume…
Abraham,<br />
That is a nice paper on thermal mass and the results make sense to me. The effect of thermal mass on the peak temperature is usually huge and is overlooked by simple psych chart studies like this one that focus on the % time that you can use a certain strategy fall inside a comfort polygon (rather than how much more comfortable the worst-case scenario is).<br />
<br />
Your rules of thumb for solarHeatCapacity look good and the only thing that I would clarify when you use them is that they assume clear double pane glazing without a low-E coating, which is normal for a project that is trying to maximise passive solar heating on a southern exposure.<br />
<br />
As for the time constants, they also look good, although I would add that the time constant is a function of BOTH thermal mass and thermal resistance (insulation). In the most extreme case of a high mass passivehaus, you would have a time constant around 36-48 hours. Most code compliant buildings in the US with exposed concrete floors would have a time constants around the default 8 hrs. 12 hrs seems to be a good value for a building that is a bit better than code with exposed massive floors and walls.<br />
<br />
-Chris Hi Chris,
Thanks for your de…tag:www.grasshopper3d.com,2017-09-10:2985220:Comment:18113512017-09-10T07:37:50.542ZAbraham Yeziorohttps://www.grasshopper3d.com/profile/AbrahamYezioro
<p>Hi Chris,</p>
<p>Thanks for your detailed answer. Clear to me that all these checking are just a first approach to understand the potential of the location.</p>
<p>Your explanation for the time constant makes sense and i get it. If you have time check the attached papers we published a while ago in relation to the contribution of thermal mass in the reduction of temperature in residential buildings. See the nice contribution of the heavy TM or the lower one for light TM.</p>
<p></p>
<p>As…</p>
<p>Hi Chris,</p>
<p>Thanks for your detailed answer. Clear to me that all these checking are just a first approach to understand the potential of the location.</p>
<p>Your explanation for the time constant makes sense and i get it. If you have time check the attached papers we published a while ago in relation to the contribution of thermal mass in the reduction of temperature in residential buildings. See the nice contribution of the heavy TM or the lower one for light TM.</p>
<p></p>
<p>As for the solarHeatCapacity, your description (of the 50W) is derived on a 1 Facade/Floor ratio and fully glazed. The only way to reduce it is to increase the ratio (bigger facade area). Which is not recommended (energy losses), but this is a different issue. So, roughly, we can say that 50 is the lower value. If i have less glazing area this number will be higher (right?)</p>
<p>I want to define a value list of "architectural situations", so it is easy to explain and understand. One situation can be:</p>
<blockquote><p>"Ratio facade/floor 1 & Fully glazed" = 50</p>
<p>"Ratio facade/floor 1 & Half glazed" = 75</p>
<p>"Ratio facade/floor 1.5 & Fully glazed" = 30</p>
<p>"Ratio facade/floor 1.5 & Half glazed" = 50</p>
<p>"Ratio facade/floor 0.75 & Fully glazed" = 70</p>
<p>"Ratio facade/floor 0.75 & Half glazed" = 90</p>
</blockquote>
<p>Makes sense for you something like this?</p>
<p></p>
<p>I also defined a value list for the timeConstant like this:</p>
<blockquote><p>Light Building (Mobile home) = 1<br/>Medium-light building (Cement tiles on floor) = 4<br/>Semi Heavy Building (Concrete floor + Tiles) = 8<br/>Heavy Building (Concrete floors/ceilings + Heavy external and internal walls) = 12</p>
</blockquote>
<p></p>
<p>As for the first 5-10 cm effective TM in general my assumption is that you take half of the mass to your space and half to the space above/below you. Will be interesting to do a parametric study on just the thermal mass, uninsulated and insulated to see what the depth limits effectivity will be. Interested in doing such a study together? Can be a nice work even for publishing.</p>
<p></p>
<p>Thanks a lot ... again,</p>
<p>-A.</p> Also, I have a small correcti…tag:www.grasshopper3d.com,2017-09-10:2985220:Comment:18114242017-09-10T02:56:11.926ZChris Mackeyhttps://www.grasshopper3d.com/profile/ChrisMackey
Also, I have a small correction to my post. In the formula, I should be dividing by the facade-to-floor area ratio (not multiplying. So a larger facade-to-floor area means a smaller solar requirement.
Also, I have a small correction to my post. In the formula, I should be dividing by the facade-to-floor area ratio (not multiplying. So a larger facade-to-floor area means a smaller solar requirement. Abraham,
I went and checked…tag:www.grasshopper3d.com,2017-09-10:2985220:Comment:18111772017-09-10T02:33:57.019ZChris Mackeyhttps://www.grasshopper3d.com/profile/ChrisMackey
<p>Abraham,</p>
<p></p>
<p>I went and checked the thermal mass polygon in a couple of climates where I know it has a big effect and I got results that made sense to me. Specifically, in the San Fernando Valley of Los Angeles, which has 12% of the year made comfortable, and Shiraz, Iran, which also has 12% comfortable (assuming default parameters).</p>
<p>Jerusalem also makes sense to me. There is only a maximum possible 9% of the year that is inside the polygon (you'll see this if you set the…</p>
<p>Abraham,</p>
<p></p>
<p>I went and checked the thermal mass polygon in a couple of climates where I know it has a big effect and I got results that made sense to me. Specifically, in the San Fernando Valley of Los Angeles, which has 12% of the year made comfortable, and Shiraz, Iran, which also has 12% comfortable (assuming default parameters).</p>
<p>Jerusalem also makes sense to me. There is only a maximum possible 9% of the year that is inside the polygon (you'll see this if you set the timeConstant to a very high number). The default strategyPar makes 6% of these hours comfortable and 3% without cool enough temperatures in the previous hours. This seems reasonable to me.</p>
<p>I could be convinced to change the default time constant to 12 hours (instead of 8) as I know that 12 is the default of climate consultant but that seemed really idealized in my opinion. You'll need really high exposed mass and insulation without much internal heat gain to make conditions stable for more than 8 hours in my opinion.</p>
<p></p>
<p>As for the <span>solarHeatCapacity, I get changes when I drop it down to 10 W/m2 or boost it up to 100 W/m2. It's definitely a parameter that operates on an "order of magnitude" scale and little tweaks to it won't change it too much. You can think of this number as representative of a lot of other physical properties: most notably the depth of the space being passively heated and the thermal mass of that space's materials that participate in heat exchange over the time constant. Climate consultant uses a default assumption of 30 W/m2 but, from my calculations, this is likely assuming a space that has a facade to floor area ratio that is greater than 1. If we say that we need to raise the temperature of 10 cm of an exposed concrete floor for passive heating purposes, and we have a facade-to-floor area ratio of 1:</span></p>
<p><span>Required solar flux = ((1 facade-to-floor ratio) x (0.1 m3 of concrete) x (2400 kg/m3 concrete density) x (880 J/kg-K concrete specific heat capacity)) / 3600 seconds/hour</span></p>
<p></p>
<p><span>This lands you with a required solar flux of 58 W, which is almost twice the 30 W climate consultant default. While me might say that not all 10 cm of concrete participates over the course of a default 8-hour time constant (most of the action is probably within the first 5 cm), we also have to account for things like transmittance of solar though the window, which, for triple pane, is probably only half of the incident solar. So 50 W seemed to be a more reasonable rule of thumb from my perspective, essentially assuming a facade-to-floor ratio of roughly 1 with 5 cm of concrete participating in an 8 hour heat exchange and a little more than half of solar heat getting through a fully glazed window.</span></p>
<p></p>
<p>Let me know if that makes sense or if you have any suggestions,</p>
<p>-Chris</p> Chris,
I think i'll drop my q…tag:www.grasshopper3d.com,2017-09-07:2985220:Comment:18103242017-09-07T19:02:09.388ZAbraham Yeziorohttps://www.grasshopper3d.com/profile/AbrahamYezioro
<p>Chris,</p>
<p>I think i'll drop my question about the ThermalMass. It is a bit ambiguous, specially looking at various cities results. They can make sense. Just one location makes me wonder (Jerusalem).</p>
<p>-A.</p>
<p>Chris,</p>
<p>I think i'll drop my question about the ThermalMass. It is a bit ambiguous, specially looking at various cities results. They can make sense. Just one location makes me wonder (Jerusalem).</p>
<p>-A.</p> Thanks Chris,
On the contrary…tag:www.grasshopper3d.com,2017-09-07:2985220:Comment:18101812017-09-07T18:35:41.777ZAbraham Yeziorohttps://www.grasshopper3d.com/profile/AbrahamYezioro
<p>Thanks Chris,</p>
<p>On the contrary. Thank you for having the patience to deal with this.</p>
<p>I get and accept your explanations. make sense and are clear. I can use your arguments to explain myself.</p>
<p></p>
<p>Another (maybe last) couple of questions.</p>
<p>You have some rule of thumb (or source) for input values for the LB_solarHeatCapacity_? The default values of 50 W/m2 is for a small passive solar heated space (full glazed facade).But i'm changing the default to relatively low…</p>
<p>Thanks Chris,</p>
<p>On the contrary. Thank you for having the patience to deal with this.</p>
<p>I get and accept your explanations. make sense and are clear. I can use your arguments to explain myself.</p>
<p></p>
<p>Another (maybe last) couple of questions.</p>
<p>You have some rule of thumb (or source) for input values for the LB_solarHeatCapacity_? The default values of 50 W/m2 is for a small passive solar heated space (full glazed facade).But i'm changing the default to relatively low values and it is not affecting the results.</p>
<p></p>
<p>I have a feeling that the temperature checking you are doing for the Thermal Mass is a bit tight. Is very hard to improve. Changing the timeConstant_ in the StrategyPar affects a lot the PSH but very little the ThM. The reason i'm asking is because for some locations i know that the thermal mass has a big influence. Though, the chart shows a small one as a total value but also looking at the 3DChart plot.</p>
<p></p>
<p>Thanks again!!</p>
<p>-A.</p> Abraham,
Thanks for the feedb…tag:www.grasshopper3d.com,2017-09-07:2985220:Comment:18101042017-09-07T17:36:11.668ZChris Mackeyhttps://www.grasshopper3d.com/profile/ChrisMackey
<p>Abraham,</p>
<p>Thanks for the feedback and for helping make this component complete. I don't follow the use-case that you are trying to help by having passive solar and the internal heat gain polygons display on top of one another. I can understand why you would want to have only a PSH polygon (if you are trying to evaluate a space that has no internal heat gain). But, if the space has heat gain, you really need the PSH and Internal Heat to be added together for them to be useful. This…</p>
<p>Abraham,</p>
<p>Thanks for the feedback and for helping make this component complete. I don't follow the use-case that you are trying to help by having passive solar and the internal heat gain polygons display on top of one another. I can understand why you would want to have only a PSH polygon (if you are trying to evaluate a space that has no internal heat gain). But, if the space has heat gain, you really need the PSH and Internal Heat to be added together for them to be useful. This is why climate consultant uses this method.</p>
<p>Furthermore, I am not inclined to make this change because it means removing the functionality to have the two added together. At least in the case that you want, you can currently run two separate iterations (one with only PSH and one with only Internal Heat Gain) to get the result that you desire. If I remove the ability to have these added together, it will become impossible to evaluate a passive heated solar space that also has internal heat gain.</p>
<p>Finally, it's worth noting that virtually all buildings that are occupied by humans have internal heat gain if only from the heat of the people themselves. The same cannot be said for interior fans, evaporative cooling or thermal mass. For this reason, I feel that my current treatment of the internal heat polygon is justifiable in relation to the other polygons.</p>
<p></p>
<p>As for your question about the percentages of the cooling polygons, the thermal mass+night vent is using a similar method to the PSH polygon in that it will only count a given hour as comfortable if there were cool enough temperatures in the previous hours to "night flush." For this reason, even though the thermal mass polygon looks large, there are often a lot of hours inside of it that are not comfortable because the preceding hours are not cool enough. On the other hand, all points within the "Evaporative Cooling" or "Occupant Us of Fans" polygon are counted. So this is why the percentage is smaller for the thermal mass polygon in relation to the others.</p>
<p>-Chris</p> Hi Chris and thanks again!!
T…tag:www.grasshopper3d.com,2017-09-05:2985220:Comment:18087892017-09-05T12:24:02.905ZAbraham Yeziorohttps://www.grasshopper3d.com/profile/AbrahamYezioro
<p>Hi Chris and thanks again!!</p>
<p>This is it ... almost.</p>
<p>I would suggest to extend the PSH to the comfort polygon regardless if there is or not the internal heat gain one. In this way you can get the possible contribution of the PSH in total. This follows the same principle of the cooling polygons, where all of them converge to the comfort. Will be more consistent and flexible in this way (on my opinion).</p>
<p>As for the balance point i agree that the 12.8 gives the maximal extent…</p>
<p>Hi Chris and thanks again!!</p>
<p>This is it ... almost.</p>
<p>I would suggest to extend the PSH to the comfort polygon regardless if there is or not the internal heat gain one. In this way you can get the possible contribution of the PSH in total. This follows the same principle of the cooling polygons, where all of them converge to the comfort. Will be more consistent and flexible in this way (on my opinion).</p>
<p>As for the balance point i agree that the 12.8 gives the maximal extent and this is the default. For an example i'm working on now i get almost 15C, but i'll start to be more aware of checking this value for different examples.</p>
<p>For future versions (also the bioclimatic ... hopefully) i think that relevant inputs should be provided for realistic conditions. I need to think better how to do that and/or if it will be efficient to check against additional climatic data (thinking right now about wind speed and natural ventilation strategy).</p>
<p></p>
<p>I have another question here related to the results of the analysis. If you see the picture below, on the right side you see the total number of points that felt on each polygon. The percentages are calculated ok. So far, so good.</p>
<p>But when i see the left side of the picture (the psychometric chart) there are some things that look strange to me. For instance, the EC received 2% and the thermal mass 1.7%, and the use of fans 2%. As i see the points the thermal mass contains all the points the EC or the Fans contains and more. But it's contribution is lower. I assume you are checking ONLY that the point fell or not inside the polygon. I see that the number of points of the thermal mass is lower than the other two (153) but from the image it doesn't make sense for me. Hope i'm explaining this clear enough ...</p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2769319456?profile=original" target="_self"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2769319456?profile=RESIZE_1024x1024" class="align-full" width="721"/></a>Thanks again. This is a great addition to the component!!</p>
<p>-A.</p> Abraham,
Glad that you found…tag:www.grasshopper3d.com,2017-09-05:2985220:Comment:18088632017-09-05T03:28:53.330ZChris Mackeyhttps://www.grasshopper3d.com/profile/ChrisMackey
<p>Abraham,</p>
<p>Glad that you found the balance point input and I agree with your suggestion about the passive solar polygon. I just pushed a change to the psych chart that pulls the passive solar polygon to the edge of the comfort polygon whenever "Capture Internal Heat Gain" is not selected:…</p>
<p></p>
<p>Abraham,</p>
<p>Glad that you found the balance point input and I agree with your suggestion about the passive solar polygon. I just pushed a change to the psych chart that pulls the passive solar polygon to the edge of the comfort polygon whenever "Capture Internal Heat Gain" is not selected:</p>
<p><a href="https://github.com/mostaphaRoudsari/ladybug/commit/559cdb46ae38eff5390d32bb26332efa1a41e736" target="_blank">https://github.com/mostaphaRoudsari/ladybug/commit/559cdb46ae38eff5390d32bb26332efa1a41e736</a></p>
<p>I am aware that 12.8 C is a relatively low balance point and I can say that, in my personal experience, the lowest balance point that I ever found was 10 C for a well-insulated cafeteria, while the highest balance point that I have ever found was 18 C for a pretty poorly insulated residence. I got the default balance point of 12.8 C from climate consultant, which uses the same default value. I am open to changing it but I can say that balance points of 12.8 C are somewhat common in the colder part of the world where I live, where the building codes keep the insulation high. I'd agree that the default polygon is definitely more of a "maximum possible potential" from internal heat gain capture but I would say that all of the strategy polygons on the chart are following a similar "maximum possible" principle. If you feel that we should be showing realistic implementations of each strategy rather than ideal ones, we can discuss it here further.</p>
<p>-Chris</p> Hi Chris,
I get now where is…tag:www.grasshopper3d.com,2017-09-04:2985220:Comment:18085312017-09-04T08:26:25.573ZAbraham Yeziorohttps://www.grasshopper3d.com/profile/AbrahamYezioro
<p>Hi Chris,</p>
<p>I get now where is the source of the Internal Heat Gain. It comes from the StrategyPar component. So the polygon extend from the lower limit of the comfort polygon until the bldgBalancePt.</p>
<p>As the hint of the bldgBalancePt says it assumes a rather good insulation and a large number of internal heat sources (which can be proper for maybe office buildings or schools) to get to the default 12.8C default value. I would say that, going to the other extreme (low loads and no…</p>
<p>Hi Chris,</p>
<p>I get now where is the source of the Internal Heat Gain. It comes from the StrategyPar component. So the polygon extend from the lower limit of the comfort polygon until the bldgBalancePt.</p>
<p>As the hint of the bldgBalancePt says it assumes a rather good insulation and a large number of internal heat sources (which can be proper for maybe office buildings or schools) to get to the default 12.8C default value. I would say that, going to the other extreme (low loads and no insulation) we can assume something like 16-18C?</p>
<p></p>
<p>Independent of that i think that the PSH polygon should extend to the comfort one and not just to the IHG, as for instance the cooling strategies do.</p>
<p></p>
<p>Playing with the PMVComfortPar PPD thershold can also illustrate the differences between building types (for instance offices should be 10 and residential can be 20). For the purposes of explaining the meaning of the strategies polygon sizes.</p>
<p></p>
<p>Thanks,</p>
<p>-A.</p>
<p></p>