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#1089224 - 14/03/2012 22:10 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
October indoor climate control (again)

Where I live, (NW Slopes, NSW) October is a month when it is not clear whether house comfort calls for heating or for cooling.

There is more to be learned from my graph in Post #1024990 by adding separate trend lines for the two data sets: the earlier set with night purge ventilation, and the later set without it.

As I said, ceasing to use night purging in October raises the indoor temperature that month well above the minimum temperature for comfort.
The trend lines I have now added can be used to estimate how much the temperature has been raised. You can see it is tricky. The two trend lines have different slopes. When doors are opened to admit cool night air, the indoor temperature varies from year to year as much as the outdoor temperature does. When doors are kept closed, the house is well sealed against outdoor temperature changes.
Cancelling the night purge when the outdoor temperature is 18 degrees would raise the indoor temperature by 1.7 degrees; doing so at 19 degrees would raise the indoor temperature by only 0.7 degrees.
In broad terms, cancelling the night purge in October improves indoor comfort by raising the temperature about one degree. If the month happens to be very cold, the improvement is much greater, preventing indoor temperatures that would be far too cold.
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#1089858 - 15/03/2012 21:13 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
House-warming should start in March

For a week (to 13/3/21), my house has been too cool for comfort. According to the Adaptive Comfort Standard (explained here and here)
the 80% minimum comfortable temperature here is 21.9 degrees on March 1, 20.7 degrees on March 31, and 21.3 degrees as an average for the month. On Thursday the 8th, my indoor minimum was down to 17.3, and even the indoor maximum (21.4) was at the comfort limit.
I responded by wearing warmer clothes (clo up to 0.42 from 0.18) and using two blankets rather than none.

This cold snap led me to review the management of my house in the month of March. The sun begins to enter my north windows giving solar heat gain about now, March 13. I add to this effect by making various changes. From an earlier post :
"I have reset the timer for the curtains to let the sun in, closed the clear-story windows to keep warm air in, and adjusted the awnings [on porches] to convert shaded breeze-ways to sun-traps. In the clear-story spaces I have re-directed the fans [from outwards to help stack effect, to] downwards [to circulate warm air], removed the timers, and set the fan thermostats to 26 degrees." I also cease purging the day's hot air by opening doors and windows at night.
I have been making these changes on March 31 or April 1.

To review my practice for changing to a winter warming regimen, I made this graph comparing March indoor temperatures with those outdoors for each of 14 years.

The Comfort Minimum line for March is shown, at 21.3 degrees. The Comfort Maximum line would be off the graph at 28.3 degrees. The Comfort Neutrality ("best") line shown is half-way between the others, at 24.8 degrees.
All of the indoor mean monthly temperatures are in the Adaptive Comfort Zone, but only the value for 2000 is even slightly above neutrality. The observed mean is 1.2 degrees below this ideal value. [The value shown for this month (March 2012) is for the first 12 days: the value for the whole month may well become the lowest.]
The house would become more comfortable in the month of March if the indoor temperature could be raised by one or two degrees.

In a post above , I made a similar graph for October months.

I reason that, if cancelling the night purge in October raises the indoor temperature by about one degree, it will give a similar result in March.
From now on, I propose to operate the house in its winter regimen of solar gain and conserving heat for the eight months March to October, and in its summer regimen of night purge and rejecting heat only in the four months November to February.
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#1089957 - 15/03/2012 23:59 Re: Indoor Climate [Re: Surly Bond]
Vinnie Offline
Meteorological Motor Mouth

Registered: 17/05/2006
Posts: 6321
Loc: Near Yeppoon
I know my posts on this thread many pages back weren't as technical but here goes anyway.

Our new place here in Yeppoon is brick veneer vs double brick in Perth.

We have a thermometer at the front of the house (west) , back of the house (east) and in the middle. It usually is about 28 degrees at the front in the afternoon most days, 27 in the middle and 26 deg at the back. There is insulation all around.

Our house is weird in that when it is closed it starts to heat up about 0.5 deg in 30mins . In Perth, with double brick the house felt quite cool when it was closed during the day . In this house I need to keep it open and let the breezes flow.


Edited by Vinnie (15/03/2012 23:59)
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#1090049 - 16/03/2012 09:08 Re: Indoor Climate [Re: Vinnie]
DaveM Offline
Meteorological Motor Mouth

Registered: 21/05/2001
Posts: 9833
Loc: Bathurst NSW about 700 m asl
Gee SB - I'm a bit different to you - I try to keep the house below a max of 20 or 21 for daytime and open up when the outside temp falls below the level inside. I'm quite happy at the moment if I can get the house down between 14 to 16 overnight - which is happening now most nights.

I mean I'm different not in baseline thinking (because I think we're on similar paths) but because my preferred temps and comfort levels are different. smile

I only still pull a blanket all the way up sometime during the night at this point. That will change over the next few weeks though. Only one night so far was I tempted to put a very thin quilt on the bed - I did it but took it off again for the blanket about 2 am. smile

Sometime in the next few weeks though the approach will start to reverse - leave curtains open for daytime - close at night - not too far away now but not happening yet - still actively trying to cool the house.

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#1090811 - 17/03/2012 09:48 Re: Indoor Climate [Re: Vinnie]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
Hi Vinnie
Brick veneer houses do heat and cool rapidly, much like weatherboard houses. If built without insulation, the bricks give a certain amount of thermal mass to the house helping to even out temperature changes, but insulation inside the brickwork stops that.
You have moved to a different climate. Perth is temperate and Yeppoon tropical. Yeppoon is cooled by easterlies from the sea all year, while Perth gets the "Doctor" only sometimes, on summer afternoons. If you study your climate in depth, I think you will find more about how to achieve indoor comfort. As you say, the main thing is to use the cooling breeze.
Thermal mass above floor level in that climate would not do much for comfort. However, there was some research done in Townsville showing that using air cooled in the subsoil might help.

Is it possible that the temperature gradient across your house is due to a cool easterly breeze?
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#1090830 - 17/03/2012 10:18 Re: Indoor Climate [Re: Surly Bond]
Vinnie Offline
Meteorological Motor Mouth

Registered: 17/05/2006
Posts: 6321
Loc: Near Yeppoon
Think so, SB. The lounge room is at the front (west) as are the parents bedroom and they are warmer at this time of the year due to the E'ly component of the wind not really reaching that far.

I didn't think Yeppoon was cooled by easterlies "all year" eg in winter.





Edited by Vinnie (17/03/2012 10:19)
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#1092590 - 19/03/2012 20:07 Re: Indoor Climate [Re: DaveM]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
Hi DaveM
Yes, I am sure we are on similar paths. Your winter is less sunny, and you seem to handle the cold a bit better.
I think it is hard for a person to "change gear" at the time when keeping warm suddenly makes more sense than to continue trying to keep cool, which has become a habit through the summer.
I set my house up for keeping warm last week (11-12/03/12), I wondered whether it was going to feel comfortable. At first it felt a bit warm and stuffy, but I got used to it. I have not needed blankets again.
The indoor mean temp is now back to 24.5, as it was at the start of the month. The outdoor mean was then also 24.5, but is now only 22.5.
Re-setting the house has definitely made a difference.
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#1103575 - 10/05/2012 15:43 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
Midwinter and Midsummer Solar-Passive
Temperature range graphs

These graphs summarise the way a solar-passive house without heating or air-conditioning performed in two sample periods, one in midwinter (16/6/10 to 16/7/10) and one in midsummer (15/1/11 to 14/2/11). For these periods, I have modelled the daily house response to weather changes (See notes below.)
The house is at Manilla (30deg 44.747S; 150deg 43.813E; 370m Alt) inland from the divide on the North-West slopes, NSW. Photos are here.
Outdoor temperature is taken in the Gill screen shown in the photo. Wall temperature is taken at head height on a stud wall in the middle of the house. Floor temperature is on a tiled floor directly below. "Heat Bank" temperature is taken in subsoil 750 mm below that. Subsoil temperature (outdoors) is taken 750 mm below the surface of garden soil 10 metres from the house. Maximum and minimum temperatures for adaptive comfort are also shown.

In the midsummer period, outdoor air temperatures ranged from too cold to far too hot, with the average a little on the warm side. The subsoil temperature (as in a shallow grave) was very comfortable. The house moderated the outdoor temperature by insulation, shade trees, windows shaded by eaves, curtains closed in day-time, and stack-effect ventilation at night. Indoor temperatures were near the middle of the comfort zone. The floor was cooler than the wall, because cold night air creeps along the floor, and because the heat bank kept some winter coolness.
In the midwinter period, outdoor air temperatures ranged from a bit too cold to thirteen degrees too cold. The outdoor subsoil temperature was several degrees too cold. Indoor temperatures were raised above the comfort minimum. Heat from sunshine was admitted through north windows, trapped by insulation and by curtains closed at night, and stored in thermal mass. With heat kept in the house, the wall, floor and heat bank came to the same temperature.

Notes.
This is part of a set of Posts modelling indoor temperatures of the house at the coldest and hottest times of the year.

I posted midwinter climate data (16/6/10 to 16/7/10) in Post #874144
I modelled the midwinter indoor conditions in Post #877256, #878964, #882793, #890247, #890751 and #902382

I posted midsummer climate data (15/1/11 to 14/2/11) in Post #975535 and #975647 .

After a year's delay, I will now model that midsummer data.
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#1128207 - 23/09/2012 19:10 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
Day-time purge for more warmth in spring
A year ago, I presented a graphical log of one year's indoor and outdoor 7-day mean temperatures.

The 7-day mean indoor temperature remained almost entirely within the comfort zone throughout the year. From time to time the temperature fell briefly below the comfort zone.
As shown here , indoor temperature seemed to be governed, to a large extent, by the temperature of the edge-insulated thermal-mass solid "heat bank" below the floor.

This heat bank stabilised the house temperature. In that year, its summer maximum (7-day mean) temperature was only 23 degrees, 8 degrees lower than the outdoor air maximum (31 degrees), and its winter minimum was 17 degrees, 10 degrees warmer than the outdoor air minimum (7 degrees).
This stabilisation came at the cost of the effect being delayed (a lag). While sudden changes in outdoor temperature seemed to affect the heat bank within two or three days, seasonal changes were delayed more than a month. The air was coolest in early July, but the heat bank was coolest in early September. As a result of this delay, the house sometimes struggled to maintain enough warmth for comfort from late winter through spring to early summer.
I have mentioned this problem in posts beginning with #1011604.

The day-time purge experiment
This year spring began very cold but, unlike spring last year, it has been sunny.
I have begun an experiment to find whether I can raise the temperature of the heat bank. If successful, the house may be better protected against later spells of cold cloudy weather.
While the house is warmed in the cold season by sunshine admitted through the north windows, not much is admitted in spring. The eaves, designed to exclude sunshine from mid-October, do not let much in during September either. Trapping solar radiation, however, is not the only way to bring in heat.
During Septembers, indoor air temperatures have been about 20 degrees, rising one degree higher by day and falling one degree lower by night. During half the days of September (on average) the maximimum outdoor air temperature rises above 24 degrees. It often stays above 24 degrees for several hours in a day. Whenever I can, I plan to open doors and windows for the periods of such high outdoor temperature. The procedure is the same as for the "night purge" in summer. Instead of using cold night air to strip heat off the exposed surfaces of thermal mass materials, I will use warm afternoon air to spread heat on them. Usually, the process will be helped by the afternoon south-west breeze carrying the air through the house. At night there is very seldom any wind.
Opening doors and windows is a complication I would rather avoid. Some doors do not have effective door-stoppers. After the first three days, I am considering whether opening only a couple of the most convenient doors will provide enough draft.
Already, the room and heat bank temperatures seem higher than would normally be expected.
On warm spring days I don't need this warm air for my day-to-day comfort. This project is strictly to ensure that the house remains comfortable when the weather turns foul.
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#1159829 - 18/01/2013 14:34 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
My solar-passive house achieves comfort in a climate of temperature extremes. It does so with very little interference by me, and very little energy use.
I have now described in detail how it does it in another forum:
http://www.ata.org.au/forums/topic/3/page/7?replies=192#post-37236
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#1165930 - 26/01/2013 13:02 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
There is discussion on how homes have coped with the recent extreme heat wave here.
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#1167729 - 28/01/2013 00:14 Re: Indoor Climate [Re: Surly Bond]
Rolling thunder Offline
Weatherzone Addict

Registered: 08/12/2011
Posts: 1152
Loc: Findon, Adelaide.
Haven't read all the posts on this topic, but I find the indoor temps quite interesting!
The house we're in atm, is quite modern, Single story, 2 bedroom, moved in 2 1/2 months back and is only about 6-7 months old. Single brick.

The room I'm in faces a Easterly direction, and cops the sun first thing in the morning, for the first month of living here, I would wake up in what felt like an oven! Indoor temps were about 31-32, this was around 8am/9am on 35+ days. Ended up buying a "Cane" type window shade. Have found it very helpful, and on 35+ days, the temp is only about 28 when i wake up.

I've been monitoring the indoor temp for the last month, and the average temp is about 26c, though it hovers between 24-29c, this is depending on stuff such as, the front door being open, fan being on, fan being off, etc.

Am waiting for winter, to see what the ID temp will hover around.
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Jan: 14.4mm YTD: 368.3mm
Feb: 6.7mm
March: 17.8mm
April: 24.1mm
May: 70.5mm
June: 49.2mm
July: 69.2mm
Aug: 59.8mm
Sept: 22.9mm
Oct: 13.3
Nov:

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#1168217 - 28/01/2013 17:55 Re: Indoor Climate [Re: Rolling thunder]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
Hi, Rolling Thunder
I hope you get some interesting results. You have a new house, which will have had to comply with rules intended to make it waste less energy. Unfortunately, most people perversely do their best to subvert the rules.
As you see, I post on two forums. I use this forum for items about indoor climate related to outdoor climate. For items about houses designed for comfort without much energy use, I post on the Alternative Technology Association site, particularly in the forum "Low-energy Houses".
I think you will find a lot of interesting stuff on both sites.
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#1168417 - 28/01/2013 21:35 Re: Indoor Climate [Re: Surly Bond]
Rolling thunder Offline
Weatherzone Addict

Registered: 08/12/2011
Posts: 1152
Loc: Findon, Adelaide.
Thanks SB, that site is quite interesting!
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Member of the Facebook page, Mid North Storms grin

Jan: 14.4mm YTD: 368.3mm
Feb: 6.7mm
March: 17.8mm
April: 24.1mm
May: 70.5mm
June: 49.2mm
July: 69.2mm
Aug: 59.8mm
Sept: 22.9mm
Oct: 13.3
Nov:

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#1183176 - 13/03/2013 21:24 Re: Indoor Climate [Re: Surly Bond]
Rolling thunder Offline
Weatherzone Addict

Registered: 08/12/2011
Posts: 1152
Loc: Findon, Adelaide.
8 days of 30+ degrees here, and the indoor temperature was wildly high, hovered around the 29-33c region for most of that time! Something to do with the high humidity? It was very un-adelaide like, with dewpoints of 14-20c on those days. We've had runs of high temps, and the ID temp hovered around 27-29, but that was with dry heat.

Does outdoor humidity effect ID temps?
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Member of the Facebook page, Mid North Storms grin

Jan: 14.4mm YTD: 368.3mm
Feb: 6.7mm
March: 17.8mm
April: 24.1mm
May: 70.5mm
June: 49.2mm
July: 69.2mm
Aug: 59.8mm
Sept: 22.9mm
Oct: 13.3
Nov:

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#1183239 - 14/03/2013 08:53 Re: Indoor Climate [Re: Surly Bond]
DaveM Offline
Meteorological Motor Mouth

Registered: 21/05/2001
Posts: 9833
Loc: Bathurst NSW about 700 m asl
My house is dropping most nights to about 16 or 17 and gets up to about 22 or 23. In the next few weeks I will switch over to leaving the curtains fully open in the day to try and get the house up to 20 by evening.

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#1183576 - 15/03/2013 09:34 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
Rolling thunder
I don't think that humidity has any effect on indoor (dry bulb) temperatures (DBT).
However, at around 30 deg, humidity begins to have a very big effect of comfort (according to theory).
From 19 deg to 30 deg,the humidity limit for comfort comes at a dew point of about 17 deg, regardless of the temperature. This makes the maximum comfortable relative humidity fall from 90% at 19 deg to 45% at 30 deg.
About 30 deg DBT, "Standard Effective Temperature" (SET) makes relative humidity much more important to comfort. If you can just handle 30 deg DBT at 45% humidity, you could equally well handle 28 deg DBT at 70% humidity or 32 deg DBT at 20% humidity.
Perhaps this helps explain why you were less comfortable this time.
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#1183578 - 15/03/2013 09:54 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
DaveM
This is the first time I have closed up the house for winter as early as 1st March.
It has worked well, helped by very low temperatures in recent weeks.
I February,when I was still trying to keep the heat out, indoor temps were between 23 and 24.5 deg, when I would have preferred 25 deg (in theory). I needed a blanket on six nights.
In March, so far, indoor temps have stayed close to 25 deg.
I have not needed a blanket, and on several nights I kept the bedroom window open. Twice I used a bedroom fan all night. That means I am slightly over-heating the house now, so it will be warm enough in winter.
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#1183870 - 16/03/2013 18:36 Re: Indoor Climate [Re: Surly Bond]
GrizzlyBear Offline
Weatherzone Addict

Registered: 23/06/2011
Posts: 2359
Loc: Yetholme [1180m] Central Table...
Surly, surely what you do now can have no effect on the house temperature beyond a couple of weeks?. With my house I would say after about 3 days would make no difference what I have done 3 days ago and this is a very well insulated house. However I am not on a slab which could extend residual heat to at least a week. The only way you could affect temps 2-3 month ahead would be if your house was mostly underground, but then it would depend on the ground temps more than what you do anyway.

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#1185920 - 25/03/2013 00:14 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2067
Loc: Manilla, near Tamworth NSW
Thanks for stirring me up, GrizzlyBear. Some things suggest to me that I can influence the house temperature more than a week ahead.

Lags in annual cycles
While my house is not "mostly underground", it is affected by heat flows deep below it. I have sensors at 0.75 metres both under the floor ("Heat Bank") and in the garden ("Outdoor Subsoil"). At that depth, daily temperature cycles can just be detected. An annual temperature cycle is likely to extend down to about 15 metres, where the temperature (at this site) would be a constant 20 degrees. Others have pumped water or refrigerant down to such depths to access useful stores of heat (or coolness). I use the simple, cheap heat flow by conduction.

Heat flows very slowly in soil and rocks. This table shows how the annual maximum and minimum temperatures at 0.75 metres below the surface lag behind maximum heating at the summer solstice and minimum heating at the winter solstice. The daily mean air temperature also lags the solstice by 35 days in summer, but only by 18 days in winter, for an average of 27 days. The Outdoor Subsoil lags about 39 days, and the Heat Bank 58 days.
I believe the 2-month lag in temperature response of the Heat Bank is due to the way the house reduces, controls, and damps down heat flows. The long lag comes with a very small annual temperature range in the Heat Bank: only 4.9 degrees, which is less than 40% of that of the subsoil outdoors.

Summer and winter cosine curves
Until recently, I would change the house to its solar-gain regimen on the 1st of April, and change it back to the night-purge regimen on the 1st of October. This broke the annual temperature cycle of the Heat Bank into two distinct parts, separated at those dates. For several months leading to each change-over date, the heat bank temperature followed a smooth cosine curve. I found I could fit two curves that had the same amplitude and phase, and differed only in the summer curve being 2.7 degrees cooler than the winter curve.

Exponential transitions
After each change-over date there was a transition period. This is a very simple linear system, where a step input leads to an exponential response. Such a system, has a Time Constant (tau) that causes the response to be 63% of its final value after an interval of tau units, and 99% (practically 100%) of its final value after an interval of 5 tau units. I fitted exponential curves to each of the two transitions, with the results shown. The time constant for the autumn transition was 14 days, with the transition complete at about 70 days. For the spring transition the time constant was about 33 days, with completion taking more than 100 days.

The current experiment
Finding the house a little cool in March and October, I have shifted the change-over dates to 1 March and 1 November. At these dates, sun does not enter the north windows, so there will not be such a sharp step input by adding and removing radiation. So far, from January to March this year, the Heat Bank temperature has varied little from 22 degrees.
I expect (in a "normal" year) that the Heat Bank will be warmer than before. Certainly, warming will begin earlier and end later. Perhaps the mid-winter part of the curve will continue to match the "Winter model" as before, but perhaps that part will be warmer too. I don't know.
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