Old Koreelah Posted January 2, 2018 Posted January 2, 2018 If you put PV or hot water collectors on all the illuminated space on your roof you don't need to agonise over colour - unless you are concerned about the opinions of the man on the moon. You're on the right track, Col. The more of our roof we cover up, the better insulated our homes. If that roof covering pumps power into the grid, all the better!
SDQDI Posted January 2, 2018 Posted January 2, 2018 You're on the right track, Col. The more of our roof we cover up, the better insulated our homes. If that roof covering pumps power into the grid, all the better! We are hoping to do some house extensions in the next year or two and I have been seriously considering taking our home off the grid altogether. It is costing us over 2000$ a quarter now with 600 odd dollars just going to gaurentee of supply. I looked into going solar and connect it to the grid but a few things are pushing me away from that. Firstly our planned extension will be directly underneath the power line that supplies our house so I will have to have that removed, I had planned on putting it underground but the cost of that goes a long way to setting up the solar. Secondly, I discovered the tesla powerwall, a battery setup which has a 10year warranty. 10 years of paying over 2000 a quarter is over 80000$ Which more than pays for itself. Thirdly if setup correctly you don't have the power outage problems that are grid related. 1
old man emu Posted January 2, 2018 Author Posted January 2, 2018 Tesla's storage battery system in South Australia has shown itself to be a motza better than traditional power generation methods for dealing with above base level demands. It was always only a matter of time before storage batteries became efficient enough to be an economically viable component of the electricity supply grid. And I imagine that the current price of a domestic solar power system would be way below what it was 15 or so years ago. Because of the astronomical price of electricity last summer, this summer we have hardly used the air conditioner in the house. Great comfort in 35 - 40 degree heat ... NOT!
derekliston Posted January 2, 2018 Posted January 2, 2018 Amazing how off track these threads can get!
nomadpete Posted January 2, 2018 Posted January 2, 2018 Yeah, but it keeps the conversation going..... 1
spacesailor Posted January 3, 2018 Posted January 3, 2018 That doesn't work as PV etc, need to be on the correct side to maximize efficiency. which leaves three sides naked. "Here are some sample albedo values. The range of possible values is from zero (totally unreflective) to one (fully reflective). New asphalt, 0.04 - 0.05 Aged asphalt, 0.1 - 0.12 Bare soil, 0.17 Deciduous trees, 0.15 - 0.18 Green grass, 0.25 Aged concrete, 0.2 - 0.3 New concrete (traditional), 0.4 - 0.55 New concrete with white portland cement, 0.7 - 0.8 Water, 0.03 - 1.0 Soil (Dark/Wet) 0.05 Soil (Light/Grey) 0.4 Sand 0.15 - 0.45 galvanized steel - 0.24 terra cota tile - 0.28 tar & gravel - 0.33 Notice that the good old terracotta tile has an higher albedo than trees, so the old areas of Sydney might be cooler than the the bush they replaced." This thread was about houses heating the air! Which includes whats on MY roof. spacesailor
derekliston Posted January 3, 2018 Posted January 3, 2018 Yeah, but it keeps the conversation going..... True.
derekliston Posted January 3, 2018 Posted January 3, 2018 That doesn't work as PV etc, need to be on the correct side to maximize efficiency.which leaves three sides naked. "Here are some sample albedo values. The range of possible values is from zero (totally unreflective) to one (fully reflective). New asphalt, 0.04 - 0.05 Aged asphalt, 0.1 - 0.12 Bare soil, 0.17 Deciduous trees, 0.15 - 0.18 Green grass, 0.25 Aged concrete, 0.2 - 0.3 New concrete (traditional), 0.4 - 0.55 New concrete with white portland cement, 0.7 - 0.8 Water, 0.03 - 1.0 Soil (Dark/Wet) 0.05 Soil (Light/Grey) 0.4 Sand 0.15 - 0.45 galvanized steel - 0.24 terra cota tile - 0.28 tar & gravel - 0.33 Notice that the good old terracotta tile has an higher albedo than trees, so the old areas of Sydney might be cooler than the the bush they replaced." This thread was about houses heating the air! Which includes whats on MY roof. spacesailor No quarrel with that, but Tesla batteries, back to grid solar etc. Still interesting but definite deviation from basic thread!
Glenn Wilson Posted January 3, 2018 Posted January 3, 2018 As a re If you fly gliders out of Camden, or use the airspace southwest between Bankstown and Camden, I wonder if you can give me some information?Have you noticed any changes in the strength or direction in the winds, or in the behaviour of thermals over the past five years or so? The background for my question is that, over the past five years, there has been an explosive increase in the area which has changed from pasture land to residential use. The majority of houses which have been built have dark coloured roofs. What I am wondering is, "Has the heat stored in these dark coloured roofs due to their low albedo resulted in increased heating of the air moving over the residential areas, thereby increasing the size and strength of thermals, and increasing the strength of the afternoon nor'easterlies. Albedo is the measure of diffusive reflection of solar radiation out of the total solar radiation received by a body. A high albedo means it reflects a lot of solar energy and a low albedo means it absorbs a lot of solar energy Here are some sample albedo values. The range of possible values is from zero (totally unreflective) to one (fully reflective). New asphalt, 0.04 - 0.05 Aged asphalt, 0.1 - 0.12 Bare soil, 0.17 Deciduous trees, 0.15 - 0.18 Green grass, 0.25 Aged concrete, 0.2 - 0.3 New concrete (traditional), 0.4 - 0.55 New concrete with white portland cement, 0.7 - 0.8 Water, 0.03 - 1.0 Soil (Dark/Wet) 0.05 Soil (Light/Grey) 0.4 Sand 0.15 - 0.45 galvanized steel - 0.24 terra cota tile - 0.28 tar & gravel - 0.33 Notice that the good old terracotta tile has an higher albedo than trees, so the old areas of Sydney might be cooler than the the bush they replaced. And I'll castrate the first bloke who introduces libido to the discussion. As a regular viewer of the National Rainfall Radar page on BOM, I often notice a concentration of cloud/rain/storms around Sydney, Melbourne and the built up areas around Brisbane/SEQ, especially with a bit of temp and humidity around.
spacesailor Posted January 3, 2018 Posted January 3, 2018 G W. But there's less rain hitting our parched grass!. spacesailor 1
old man emu Posted January 3, 2018 Author Posted January 3, 2018 As a regular viewer of the National Rainfall Radar page on BOM, I often notice a concentration of cloud/rain/storms around Sydney, Melbourne and the built up areas around Brisbane/SEQ, especially with a bit of temp and humidity around. I can't speak for Brisbane, and the poil of da sout, but you have to live in the Sydney Basin to understand the movement of thunderstorms from the southwest to the north east. There are three major rivers around and through the Basin: Nepean/Hawkesbury, Parramatta, Georges. Thunderstorms develop on the southwestern slopes on a line roughly between Goulburn and Bathurst. As they move in a northeasterly direction and cross the Great Divide, large cells break up and those formed near Goulburn tend to track from Picton to Campbelltown down the Georges River catchment. Those that form along the Golspie Booroowa line first move down the Nepean Valley, and may split with the daughter cells going down the Parramatta River. So the heavy rain falls northeast of the Campbelltown to Bankstown line; along the Nepean/Hawkesbury valley, taking in The Hills District and Central Coast. In the past, Sydney's relief from high summer temperatures was the Southerly Buster, which tracked up the coast from the Illawarra, bringing strong winds and short, sharp periods of heavy rainfall. The effects of the Southerly Buster were not seen much more than 20 kms from the coastline. The majority of residential development in the Sydney Basin is occurring away from these natural storm paths. As a matter of fact, much of the southwest of the Basin, from Bankstown to Camden, Camden to Penrith is in a rain shadow. Hence to original impetus for this thread.
Old Koreelah Posted January 3, 2018 Posted January 3, 2018 We are hoping to do some house extensions in the next year or two and I have been seriously considering taking our home off the grid altogether.It is costing us over 2000$ a quarter now with 600 odd dollars just going to gaurentee of supply. I looked into going solar and connect it to the grid but a few things are pushing me away from that. Firstly our planned extension will be directly underneath the power line that supplies our house so I will have to have that removed, I had planned on putting it underground but the cost of that goes a long way to setting up the solar. Secondly, I discovered the tesla powerwall, a battery setup which has a 10year warranty. 10 years of paying over 2000 a quarter is over 80000$ Which more than pays for itself. Thirdly if setup correctly you don't have the power outage problems that are grid related. A hopeful sign: Modern homes trapping heat 'like a plastic bag'
DenisPC9 Posted January 4, 2018 Posted January 4, 2018 Amazing how off track these threads can get! We have some skilled navigators here
old man emu Posted January 5, 2018 Author Posted January 5, 2018 We have some skilled navigators here As always, Off Track, Over Time.
old man emu Posted January 5, 2018 Author Posted January 5, 2018 Finally found a good pictorial description of the movement of air masses in the Sydney Basin. The material was prepared about 18 years ago, but it still reflects the current conditions and the basis for my querying the adverse effects of massive residential development in the south-west of the Basin. Air Pollution in Sydney Basin Please don't comment on the fact that the site it got this from is an Anti-Second Airport one.
Yenn Posted January 5, 2018 Posted January 5, 2018 One of the reasons the cities are where they are is that the weather was suitable when they were established, by that I mean there was reasonable rainfall. Just move a short distance away and conditions change.
old man emu Posted January 5, 2018 Author Posted January 5, 2018 Well, Sydney was established where it is because it provided a much safer anchorage than Botany Bay, which was going to be the site for the settlement, based on the glowing reports of Joseph Banks. It was too bad that after leaving Botany Bay, Capt Cook didn't poke his nose into Port Jackson (Sydney Harbour) before heading home. As to the weather, if you read the diary entries for January 26, 1788, you will learn that after a very hot day, the new arrivals encountered massive thunderstorms with heavy rain and strong winds - a Southerly Buster, typical for late January. I wonder how the settlement would have fared if the First Fleet was still anchored in the unprotected waters of Botany Bay on that day. 1
red750 Posted January 5, 2018 Posted January 5, 2018 This might keep the house cooler and aircon charges down, but how will it affect the air currents?
old man emu Posted January 6, 2018 Author Posted January 6, 2018 This might keep the house cooler and aircon charges down, but how will it affect the air currents? If the roof coating resulted in a higher albedo than the original, then infrared radiation (what makes things hot) would be reflected before it had the chance to increase the temperature of the roofing material, which in turn would provide less temperature gradient between the roofing material and the air in contact with it. The air would not heat as much as it did with the original roof surface, so it would not tend to become less dense and rise. It is rising air that initiates heat circulation and wind generation in the atmosphere. 1
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