[Greenbuilding] Swedish solar-heated village

Wed Nov 25 17:07:18 CST 2015

In Germany in the eighties there weren't very many clothes driers. But
yeah.

On Wed, Nov 25, 2015 at 2:41 PM, John Straube <jfstraube at uwaterloo.ca>
wrote:

> In Ontario they "communicate" that with a doubling of electric rates
> during peak hours. Clothesedriers are even bigger peak draws than
> ‎washers...
>
>
> Sent from my BlackBerry 10 smartphone on the Bell network.
> *From: *Reuben Deumling
> *Sent: *Wednesday, November 25, 2015 15:38
> *To: *Green Building
> *Reply To: *Green Building
> *Subject: *Re: [Greenbuilding] Swedish solar-heated village
>
> Growing up in Germany we were exhorted to, for instance, *not wash clothes
> on Mondays* for purposes of load balancing. Traditionally German housewives
> did the laundry on Monday and German washing machines heat their own water,
> thus the spike the grid operators were trying to flatten. I don't see why
> we couldn't revisit this kind of communication aimed at shifting demand.
> Dishwashers gthere were/still are supposed to be run at night, etc.
>
> On Wed, Nov 25, 2015 at 12:11 PM, Dan Johnson <danjoh99 at gmail.com> wrote:
>
>> It's great to see Nick Pine back on this list. I want to point out for
>> discussion that the electrical grid has virtually no storage! The grid
>> follows load and must be balanced nearly instantaneously with dispatchable
>> generation.
>>
>> Contributing PV energy to the grid is often part of the problem, because
>> renewables often need to be curtailed when production exceeds demand. Grid
>> operators can't taper down the baseload generators every time the wind
>> picks up. The California ISO site has a lot of current information and I've
>> found it a great place to learn about the electrical grid. And this is one
>> of the most progressive operators in terms of their renewables and storage
>> mandates from the State. http://www.caiso.com/Pages/default.aspx
>>
>> Bringing this back to solar storage in winter (in California, for
>> example), when I do morning warm-up or heat during a cloudy day using my
>> electric heat-pump, the electric grid is running natural-gas-fired
>> generators at an emissions rate that is dirtier than average. This is
>> because renewables are generally not online during these periods. Check out
>> this net-demand chart from Cal ISO: the morning peak of the green line is
>> all fossil fuel, before solar comes online.
>> http://content.caiso.com/outlook/SP/duck.gif. There may be less
>> emissions and less fuel burned if I just burned the natural gas at my house
>> with a condensing appliance, as a backup to my passive systems, using no
>> storage. The chemical bonds in the natural gas provide the storage. :-)
>>
>> Any net surplus of PV from my house would occur when I don't need it to
>> power a heat-pump or A/C: these are periods when likely other houses don't
>> need it either. Net consumers would be commercial buildings, hospitals, and
>> other process loads on the grid. In one scenario, we can ramp-down the
>> fossil generators during these periods, so **here is where we can argue
>> that the homeowner's PV could be considered a carbon offset**---but no more
>> real than Terrapass. http://www.terrapass.com/. In another scenario, the
>> added power from renewables just lets us bring more loads online---total
>> load and demand grow over time! This is the opposite of what we wanted.
>>
>> Returning to grid-scale storage: it seems this is science fiction, like
>> clean coal. Euan Mearns has some great analysis of experimental pumped
>> hydro schemes in the Canary Islands.
>> http://euanmearns.com/el-hierro-another-model-for-a-sustainable-energy-future/.
>> California conducted a workshop in Jan 2014 on pumped storage and many
>> presentations from it are here:
>> http://www.cpuc.ca.gov/PUC/energy/electric/Technical_Workshop_Understanding_Current_State_of_Pumped_Storage.htm.
>> If 300 high reservoirs were built along the coast, using the ocean as the
>> low reservoir, the grid could get 572 GWh of storage, almost 1 day of
>> storage for California!
>> http://www.cpuc.ca.gov/NR/rdonlyres/1521FE3B-2FB5-4A6A-A93B-45125D6EF895/0/Barnhart20140116CPUCPHSWorkshop.pdf
>>
>> Best,
>> Dan Johnson
>> Albany, CA
>>
>> On Tue, Nov 17, 2015 at 12:06 PM, Nick Pine <nick_pine at verizon.net>
>> wrote:
>>
>>> Kimmo writes:
>>>
>>> I’m an entrepreneur that is doing research the possibility to use some
>>>> architecture ideas to heat houses in Sweden similar
>>>>
>>> to what Soldiers Grove did back in 1979. We will of-course try to
>>> modernise the design but the basic concepts are the same
>>> with the “solar attic”.
>>>
>>> Soldier’s Grove attics required moving warm air down to the lower part
>>> of the building using fans or blowers and a motorized damper, and it’s hard
>>> to store solar heat from warm air. I figure cloudy days are like coin
>>> flips, so a building that can store enough heat for 1 cloudy day can be at
>>> most 50% solar heated, with a possible max 1-2^-N solar heating fraction if
>>> it can store enough solar heat for N cloudy days in a row, eg 1-2^-5 = 0.97
>>> with 5 days of storage. Most of the SG buildings were only 50% solar
>>> heated. Why stop there?
>>>
>>> It seems to me that collecting enough heat to warm a building on an
>>> average day would be simpler with some passive solar heaters built into the
>>> south wall, eg
>>> http://www.builditsolar.com/Projects/SpaceHeating/solar_barn_project.htm
>>>
>>> Where I live near Philadelphia, PA, 1000 Btu/ft^2 of sun falls on a
>>> south wall on an average 30 F January day, so a 4 foot x 8 foot vertical
>>> south air heater with US R2 twinwall polycarbonate glazing with 80% solar
>>> transmission would gain 0.8x32ft^2x1000 = 25.6K Btu/day. With a 70 F
>>> building and a T (F) exit air heater temp and a (70+T)/2 average air temp
>>> inside the heater and a 6-hour solar collection day, the heater would lose
>>> about 6h((70+T)/2-30)32ft^2/R2 = 48T+480 Btu/day. With a constant C cfm
>>> airflow, the collector would provide 6C(T-70) Btu/day of heat to the
>>> building... 2 1 ft^2 vents with one-way plastic film flappers and an H = 8
>>> foot height difference would make C = 16.6x1ft^2sqrt(8'(T+70)/2-70)) =
>>> 33.2sqrt(T-70) cfm, and 25.6K = 48T + 480 + 200(T-70)^1.5 makes 543 = T +
>>> 4.15(T-70)^1.5, ie T = 70+((543-T)/4.15)^(2/3). Plugging in T = 100 on the
>>> right makes T = 92.4 on the left, then 92.7, then 92.7, with C = 158 cfm
>>> and a 6x158(92.7-70) = 21.5K Btu/day heat gain for the building, which
>>> might have just enough thermal mass and insulation and airtightness to cool
>>> from 70 to 60 F by dawn... 60 = 30+(70-30)e^(-18h/RC) makes RC =
>>> -18h/ln((60-30)/(70-30)) = 63 hours.
>>>
>>> And given the present low cost of PVs and inverters, we might heat the
>>> building with Mitsubishi or Fujitsu mini-split heat pumps on cloudy days
>>> (they work with an outdoor air temp down to minus 13 F), powered by PVs,
>>> using the electrical grid for storage instead of a 5000 gallon hot water
>>> tank. How many peak watts of PV would be required for space heating alone,
>>> with a COP of 3? A simulation using hourly EPW weather data could help
>>> estimate this.
>>> http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=6_europe_wmo_region_6/country=SWE/cname=Sweden
>>>
>>> Then again, a solar village could have passive solar air heaters on each
>>> house and a large common underground heat storage tank with a geodesic
>>> transparent roof and a simple drainback hydronic collector on top of a
>>> floating insulated cover under the roof.
>>>
>>> Nick
>>>
>>>
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>>
>>
>>
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