Our rain gauge this morning after a long dry spell.
I’m still pretty jet-lagged after arriving back in Sydney the day before yesterday but I’m very happy to report that I seem to have brought some rain with me. It’s been a long dry spell here (and in Montana too) with our weather station only recording a total of 41mm over the last four months. So we were thrilled to hear rain on the roof all night last night and to wake this morning to find over 35mm in the rain gauge. That’s on top of the 20mm we had yesterday so we’ve had over 55mm in the last two days, our tanks are full again and all our plants are breathing a big sigh of relief.
I also had time this morning to check our monitoring equipment to see how the Greeny Flat has been performing while I was away. I was particularly interested to see what difference the solar air heater (circled in blue above) made to our indoor temperature and humidity while we were gone.
Long-time readers will recall that I have written about our experiments with making a DIY solar air heater a number of times. In this Newsletter from May 2015 I described the thinking behind our Solar Air Heater prototype and in this Newsletter I showed some early results from trials of the system. Fast-forward two years and, just before we left on our trip to states, we decided to make the prototype into a permanent part of the Greeny Flat. This meant cutting holes in walls to allow us to duct the incoming heated fresh air across to the back bedroom on the south side of the house (this bedroom doesn’t get any sun and it’s been nice to have the added warmth in there in winter).
The quiet fan is mounted inside an insulated box placed on top of our bedroom closet.
We also added a new, quiet fan which we mounted inside an insulated box (for sound proofing), wired it into the house power and connected it to a thermostat controller.
The thermostat controller measures the temperature inside the solar air heating panel on the north wall of the house and switches on the fan when the temperature reaches the set point.
As you can see from the photo above, this new and improved system was delivering 57.1degC on a day when it was only 16.3degC outside. In other words, the Solar Air Heater was adding 40.8degC to the incoming fresh air.
This photo of our weather monitor was taken at the same time. The outside air temperature is circled.
Needless to say I was very happy with this addition to the energy efficiency, comfort and indoor air quality of the Greeny Flat while we were here in the home. But I was also interested to see what effect it would have while we were away in winter.
One of the few drawbacks of our Passive Solar house is that it works best when we are here to operate the windows and blinds correctly… as the saying goes, ‘Passive House, Active Owner’. In winter this means opening our insulating blinds during the day to let the low winter sun stream in and warm the floor slab then closing them at night to help keep the warmth inside. It’s also up to us to run our ventilation fans as much as needed in order to keep the indoor humidity down to a reasonable level (around 50%), to reduce condensation potential and maintain good indoor air quality. But when we’re not here to open the blinds during the day or run the vent fans the temperature will go down and the humidity will go up.
This was proven true two years ago when we were away for the whole month of August. According to our weather monitoring system, the outdoor temperature for that month averaged 8.5degC and the outdoor humidity averaged 67.7%. Meanwhile the indoor temperature averaged 14.4degC and the humidity 56.7%… that was without the solar air heater operating.
As it happened, we were away again for the whole month of August on our latest trip. But this time we were able to leave the solar air heater turned on. Because it is set up on a thermostat, whenever the temperature inside the heater panel gets above 40degC the fan automatically switches on and blows warm air into the house. So, even though we weren’t there to operate the blinds or the vent fans, the house was still getting some added heat and fresh air.
The results speak for themselves. During this most recent August while we were away, the outdoor temperature averaged 8.7degC and the humidity 70.8% (almost identical to August 2015) however the indoor temperature averaged 16.2degC and the indoor humidity 47.4%. This means that the Solar Air Heater by itself raised our indoor air temperature by an average of about 2degC and reduced our indoor humidity level by about 10%.
Personally I think that’s a fantastic result.
Reader Responses to ‘Cattle, Good or Bad’
In last week’s Newsletter from the ranch in Montana I attempted to address a reader named Leon’s concerns about the harm that animal agriculture is doing to the global environment. During the last week I have received a number of responses including the following from Leon…
Hi Andy,
Thanks for taking it on-board, appreciated! My partner and I are both vegan, climate is only one part; cruelty, exploitation and our health are another part too. Here are some links:
http://www.abc.net.au/news/2014-04-28/hamad-meat-the-hidden-culprit-of-climate-change/5414894
https://www.sciencedaily.com/releases/2017/09/170929093248.htm
Best wishes,
Leon
Also this from a reader named Doug
Hi Andy,
Thanks for another interesting Newsletter.
You’ve raised what can become a very heated debate by those who see domestic grazing animals as a huge cause of green house gases and those who defend the practice. A recent very thoughtful book on this issue by an Australian farmer and academic, Charles Massy, called “The Call of the Reed Warbler” is worth reading before rushing to make too many judgements on this issue.
The experience and work of another author, Allan Savory, is also worth investigating. His work is also discussed in Charles Massy’s book.
Always look forward to reading your words and hope you get as much enjoyment setting your thoughts to paper as we readers do reading them.
All the best,
Doug
And this from Chris
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