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#1000938 - 14/07/2011 18:35 Re: Indoor Climate [Re: Vinnie]
Vinnie Offline
Meteorological Motor Mouth

Registered: 17/05/2006
Posts: 6552
Loc: Mulambin , Yeppoon Central Qld
How do temps rise and fall in a brick on the outside, plasterboard on the inside house (think it is called brick veneer ?) house ?

Say if it was 32 degrees most days in summer and 22 at night most nights what would it be roughly in temperature inside the house ?

And winter ? ... as you can see I am referring to a subtropical climate with less big swings in temperature like Perth.
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#1000959 - 14/07/2011 21:40 Re: Indoor Climate [Re: Vinnie]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
Vinny, the plaster-board on the inside of the walls of your house may perhaps be on the inner brick leaf of a double-brick wall. Brick veneer houses are built of wood, with one layer of brick around the outside, mainly for show.
About one page up on this thread, the third graph, dated June, may show roughly what is going on. Both houses had indoor daily maxima higher than outdoor daily maxima, and both had smaller indoor temperature ranges. Earlier graphs are linked to that post.
In cold winter weather, the better a house meets the "Star-rating" requirements, the warmer it will be, and the less the temperature will vary in a day. Thermal mass carries heat for weeks.
As you see from the graphs, the evening temperature is actually above the average: sunrise is a much colder time of day, indoors and outdoors.
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#1002218 - 22/07/2011 09:14 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
Low daily maxima (about 15 degrees) and cloudy skies (nearly all 6/8 to 8/8) have kept this solar-passive house below the Adaptive Comfort Zone (min. 17 degrees) for a fortnight. I don't think that ever happened before.
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#1005251 - 09/08/2011 21:22 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
July Indoor Temperature 1999 to 2011
Manilla Solar-Passive House

1. Relation to Climate

I now have thirteen winters of data on indoor and outdoor climate for my unheated solar-passive house at Manilla NSW. The climate in July, the mid-winter month, has varied a lot, making the house too cold for comfort in at least one winter.

Changes in Manilla July outdoor (or ambient) climate are summarised in Post #1003619 in the thread "Observations of climate variation"

I have chosen to represent the indoor climate of the house by the mean daily room temperature measured at head height. Room temperature varies by only about three degrees during each day. Thus, year to year changes in maximum and minimum room temperatures are much the same as in the mean room temperature. July mean floor (slab surface) temperature is about half a degree cooler than room temperature, and varies only about one degree during each day.

Temperature Logs
The first graph shows that the climate variable that is best tracked by room temperature is the outdoor mean daily maximum temperature. The two patterns are alike. In particular, July 2007 was very cold, between warm peaks in 2005 and 2009. July room means were usually about 1.6 degrees higher than outdoor maxima.
Room temperature did not track outdoor mean daily minima: very cold minima in July 2002 and very warm minima in July 2010 had little or no effect indoors. In July 2002, room temperature was 20.0 degrees above the outdoor minimum; in July 2009, only 13.7 degrees.
As outdoor mean temperatures are the average of the well-fitting maxima and the poorly fitting minima, they do not fit as well as maxima.

Regressions
I have done scatter-plots and regressions of mean room temperature on each of the July climate variables of Post #1003619. The only regression with a coefficient of determination (R-squared) above 0.13 was the regression on ambient maxima (shown in the second graph):
y = 0.69x + 6.8; R^2 = 0.55
This shows room temperatures in July varying in the same sense as outdoor maxima, but only by two-thirds as much. The thermal inertia of the house carries heat over from month to month, reducing the effect of extremes of monthly climate.
I thought that, having estimated values of room temperature as a function of ambient maxima, the residual discrepancies of (actual minus estimate) might correlate with other variables, but R-squared values turned out to be trivial.
I infer that ambient maximum temperature is a serviceable proxy for solar radiation. It incorporates the effect of other variables such as cloudiness: cloudy days are the ones with low maximum temperatures. This well-sealed house achieves a higher, more comfortable temperature than ambient in winter mainly by absorbing more solar radiation and reducing heat lost as thermal radiation.

I hope the climate of future July months will be like July 2005, when the house was a comfortable 19.3 degrees, and not like July 2007, when the house was nearly 2 degrees colder: a chilly 17.5 degrees.
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#1005893 - 13/08/2011 22:17 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
July Indoor Temperature 1999 to 2011
Manilla Solar-Passive House

2. House Performance Defects

In Post #1005251 (above) I related house temperature in July to ambient climate. The best regression, that of room temperature on ambient daily maximum temperature, is poor, with a coefficient of determination of only 0.55. Could some defects be degrading the mid-winter performance of the house?

Looking at the way the points are spread on the scatter plot, the best performance relative to climate was in the middle years, 2002, 2003, 2004, and 2005. The performance was worst in the the last year, 2011, but also very poor in the first two years, 1999 and 2000, and the second-last year, 2010.
I have adapted the regression model to best fit the four July months when the house performance was best, by increasing the constant term by 0.43 degrees, giving:
y = 0.69x + 7.23
This is my model for July room temperature when the house is performing well. In those best-performing July months, mean room temperatures were about 1.7 degrees above ambient maximum temperatures.
The first graph compares this "Best Performance" model with actual temperature, and shows the discrepancy between them, the largest being -1.05 degrees in 2011. I have looked for causes for these discrepancies.

Initial defects, later fixed
(a). In April 2001 I installed an automated shutter on the large single-glazed window of the front porch. In winter this shutter is closed at night. In another forum, I have posted a graph suggesting that this raises night temperature in the porch by more than one degree, but the house temperature would be raised much less.

(b). The builder had scraped away most of the soil in front of the north wall of the house, leaving a hard clay surface. On the house wall, eight courses of bricks beneath the slab had been left exposed. In November 2000 I built the ground surface up with imported loamy top-soil to leave only four courses of bricks exposed. Later, I covered this soil with a mulch of leaves, bark and twigs from nearby trees, and planted it with ground-covers and shrubs. This work should have reduced chilling by night radiation from the soil and the lower four courses of bricks. In turn, less heat should be lost from the edge of the floor slab by conduction.

Measures (a) and (b) both protect the house against heat loss at night, which the house seems to do well in any case. However, these are the only things I can suggest to explain the relatively poor performance in the first winters. To model the actual house performance (second graph), I subtract 0.63 degrees for July of 1999 and 2000. As the mulch and plantings were probably rather ineffective in July 2001, I subtract 0.31 degrees in that month as well.

Shading of north windows by a tree
A neighbour's mature ironbark tree is only eleven metres north of this house. At first its shade did not reach my windows. The tree had been stunted, perhaps by a lightning strike, so as to stand only eight metres high. It recovered rapidly, until it is now about sixteen metres high and eight metres wide. At midwinter it casts a shadow high enough to reach both ground-floor windows and clear-story windows. This shadow lasts from early afternoon to sunset.

I have not collected data to track the progress of shading by the tree, but I may be able to find evidence of its effect if the house performance has been less affected in April and October when the shading is less. I have modelled the increasing effect of the tree's shade on the actual house performance by subtracting 0.17 degrees in July 2006, and a further 0.17 degrees each July after that.
(The sharp drop in performance between 2010 and 2011 may be due to the clear-story windows not being shaded at all until 2011.)

House July performance including "defects"
The green line on the second graph is the model of "degraded" house performance. It is based on both the changing July climate and the performance loss due to initial defects and increasing tree shading.
This model is speculative (fudged), but it points to the kinds of results to expect in the wid-winter performance of similar houses in such a climate.

For what it is worth, the regression of actual house temperature on "degraded" model house temperature is:
y = 0.99x + 0.24 __R-squared = 0.93.
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#1011604 - 11/09/2011 09:55 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
Cold September south-westerlies are keeping outdoor daily maxima below 16 degrees, 7 degrees below normal. While the wind blows (during all daylight hours) the air temperature goes as low as 10 degrees, chilling the walls and roof of the house. My double-glazing must be limiting the heat loss where the boundary layer near the glass is stripped away by the wind. The cold air gets inside, too: I can feel the draft around two west-facing doors.
On this third windy day the room temperature has fallen below 18 degrees.
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#1016838 - 03/10/2011 21:26 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
For nearly a week, outdoor daily maxima have been below 21 degrees, which is five degrees below normal. Sunday was 13.4 degrees: a near-record 12.6 degrees below normal. There was overcast with cloud near the ground and a strong wind.
The solar-passive house stuggles a bit to get warm. The eaves cut off most solar radiation now, as solar gain is not normally needed in October.
Indoor temperature is about 18 degrees day and night, on both the wall and the floor. I am back in mid-winter clothing (clo=1.04) and using two blankets on the bed. I have not needed a heater, though.
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#1024990 - 28/10/2011 22:27 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
October too early to let in cool night air

The graph compares mean October indoor temperature in my high-mass solar-passive house with mean ambient (outdoor) temperature.


I now have records for 13 October months. The climate has varied a lot in that time. The mean ambient temperature in October 2007 (20.4 degrees) was three degrees warmer than in Octobers of 2001, 2003 and 2011. This data helps me learn to manage the house in this climate.
The main way the house stays warm in winter and cool in summer is north-facing windows shaded by eaves. Sunshine is let in during winter, but kept out by the eaves from mid-October to mid-March (five months). To add to this, I change various controls twice a year:at first I changed them on October 1 and April 1.
One of the changes to increase summer cooling is purging the warm air trapped in the house by opening doors and windows each night, and enhancing the stack effect draft by blowing the air out clear-story windows, using fans set to run from midnight to 5 am.
For the first five years (coloured red on the graph) this purge of warm air was done nearly every October night. As a result, the average temperature in the house in these months was near the lower limit of the Adaptive Comfort Zone or even below it. In October 2001 the house was quite cold (18.2 degrees). This happened because the average overnight ambient minimum temperature was only 9.0 degrees, nearly two degrees below normal for the month.

Before October 2005, I decided to postpone the first night purge each year to November 1. It is clear that all Octobers from 2005 (coloured green) have average indoor temperatures well up in the Adaptive Comfort Zone.

I have now decided to begin all of the seasonal changes on November 1 instead of October 1 each year. As well as the night purge, these include re-setting several awnings for more shade, and the timers on the motorised curtains and shutter to close by day instead of by night.
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#1025050 - 29/10/2011 09:49 Re: Indoor Climate [Re: Surly Bond]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
SB, as a serious consideration, is it feasible to have your awnings automatically adjustable so as to be perpendicular to the sun's angle day by day and so maximise reflected radiation? In other words it would be like a telescope tracking stars or planets, keeping up with the changing position of the sun.

I've never heard of such a thing but it just occurred to me as I was reading your last post.

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#1025564 - 30/10/2011 19:55 Re: Indoor Climate [Re: Keith]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
Keith, it is technically feasible to have sun-tracking reflective awnings, but it is expensive and not proof against mechanical problems.
My awnings are simply put up or down twice a year, transforming porches from sun-traps to shaded breeze-ways.
As to reflection, I do have a plan to put fixed mirrors on the south fence to warm the lower south-facing walls and footings in winter with reflected solar radiation.
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#1025944 - 31/10/2011 18:42 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
A post that refers to the October outdoor temperatures shown in the above graph (3 posts up), together with a response, is in the thread "Observations of Climate Variation".
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#1029182 - 10/11/2011 13:13 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
There is discussion of indoor climate in the thread for the current month.
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#1030356 - 13/11/2011 21:59 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
Since last Thursday I have not needed to wear socks in the house. The tiles are about 22 degrees now, and very comfortable on the feet. smile
The last time I was barefoot all day was early April.
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#1039359 - 07/12/2011 10:10 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
As in many places, December weather here so far has been cold. Days have averaged 25 degrees (7 down), and nights 12 degrees (4 down).
The house is bumping along on the minimum for December comfort: 22 degrees. I am sticking with the summer ritual of opening doors at bed-time so the "night purge" will cool the structure of the house. I might need it to be cool if there is a heat wave later. It is not as if the air is particularly cold on these cloudy nights.
Usually, my summer clothing is shorts, T-shirt and bare feet, for clo = 0.18, but every evening I'm wearing trousers, polo shirt, socks and slippers, for clo = 0.45: more than twice as much for warmth!


Edited by Surly Bond (07/12/2011 10:12)
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#1041330 - 11/12/2011 07:30 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
Very high humidity indoors.
Things in sheds are soggy or rusty.
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#1043625 - 15/12/2011 00:18 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
House Doesn't Warm Much with the Climate

In the twelve years I have lived in my solar-passive house at Manilla, NSW, the climate has changed. The mean temperature for each year has varied. The low extremes were 2001 and 2008, 0.70 and 0.75 degrees low, and the high extreme 2009, 0.95 degrees high. Elsewhere, I have plotted this temperature variation as smoothed monthly values on a graph, which shows how global mean temperatures also varied in the same sense during this time.

This data set misses the fact that the house operates in distinct regimens in summer and winter: it includes only annual averages.

Here, I have simply plotted each year's mean indoor temperature against that year's mean outdoor temperature. The indoor temperature is much more comfortable.
For a climate with that mean outdoor temperature (18 degrees) the corresponding "neutrality temperature" giving best comfort is 23.4 degrees. While this falls above the top of the graph, all plotted points have indoor temperatures within the 90% satisfaction comfort zone, which extends down to 20.9 degrees.
The data points match a second-degree curve. At the coldest temperature (2008) each degree of climatic cooling brings a degree of cooling in the house. However, at the warmest temperature (2009) each degree of climatic warming brings only half a degree of warming in the house.
If the relation changes little for higher (or lower) temperatures, this house is likely to perform even better in a warmer climate. The mean temperature indoors will reach the ideal "neutrality temperature" when the climate is about two degrees warmer than in 2009.
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#1045648 - 19/12/2011 12:47 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
Originally Posted By: Surly Bond
As in many places, December weather here so far has been cold. Days have averaged 25 degrees (7 down), and nights 12 degrees (4 down).
The house is bumping along on the minimum for December comfort: 22 degrees. I am sticking with the summer ritual of opening doors at bed-time so the "night purge" will cool the structure of the house. I might need it to be cool if there is a heat wave later. It is not as if the air is particularly cold on these cloudy nights.
Usually, my summer clothing is shorts, T-shirt and bare feet, for clo = 0.18, but every evening I'm wearing trousers, polo shirt, socks and slippers, for clo = 0.45: more than twice as much for warmth!


Astonishingly, the weather is still the same 12 days later. Such a sustained period of low temperature in summer must be almost without precedent. I am staying in warm clothes.
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#1054760 - 11/01/2012 22:33 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
Recent climate change is bad for solar-passive houses

I am working up performance data for 12 years in my high-mass solar-passive house on the N W Slopes of NSW.
Summer data seem to show that the house is becoming less effective at rejecting summer heat. I think this is a result of recent climate change rather than faults developing in the house.

In summer the cooling of the house is done mainly by flooding it with cold air at night. Data show that summer temperature in the house responds to ambient minimum temperature and not to ambient maximum temperature. Thus, summer heat, felt as high daily maxima or daily means, is countered by cooler air that is near the daily minima.
In the 12 years, the summer daily maximum temperature has fallen by nearly half a degree, leading one to suppose that a well-designed house should also have cooled slightly. This has not happened. In the same period, the summer daily minimum temperature has risen by one whole degree, raising the house temperature with it. The night air cannot cool as effectively as it could in 1999.

Winter comfort in this solar-passive house has also been made worse by climate change. I showed here (3rd graph) that July daily maxima at Manilla have cooled while minima have warmed, each by about one degree in the 12 years. In a post earlier in this thread, the first graph shows that, before allowing for known defects, the modelled indoor temperature (green line) decreased by about one degree in the 12 years, falling towards the minimum for winter comfort. In winter the house is warmed by the sun at mid-day, which is now not as warm as it was. The warmer winter nights give no warmth, as so little heat is exchanged at night.

Solar-passive houses work best in climates with a high daily temperature range. Here, the daily temperature range has fallen dramatically, by about 1.5 degrees in a decade. That is degrading the performance of the house, both in summer and in winter.
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#1056547 - 15/01/2012 18:39 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
I have rugged up.

With today the coldest January day in a decade (max 23 degrees) the house is also below 23 degrees.
From shorts and bare feet yesterday, I have changed to longs, jumper, socks and slippers. In clo units, that's from 0.18 clo to 0.72 clo!
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#1077402 - 17/02/2012 23:53 Re: Indoor Climate [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2144
Loc: Manilla, near Tamworth NSW
With the summer persisting as the coolest in many years, my house is bumping along at 23 degrees, near the defined lower limit of the Adaptive Comfort Zone.
However, I have spent most evenings lately in shorts, T-shirt and bare feet, so there is really nothing to complain about.
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