solar panel output degradation?

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  Jasen.

ven so dm^3 is a weird unit. Why not liters (l)? So kg/l would have been clear.

I

the

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  Rick C. 

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What planet are you living on, that you imagine kids have to be TOLD about bicycles?

Subsistence farmers can take a few cash crops to market on bicycle (ginger or dried herbs or tea or smoked salmon) and either barter or sell-and-use-cash for the things they DON"T grow, like cellphones. They don't get food from the market, though. Neither do hunters and herders... why do you think productive peoples ARE poor? Can it be that they aren't cash-rich because they don't have much use for cash?

Substitute 'raft' for bicycle, and 'whiskey' for dried herbs, and you'll understand the Whiskey Rebellion better.

Make that a tricycle. It is amassing how large loads they transport on tricycles with muscle power only.

In order to minimize the need for external energy, the house should be built in a similar way both in cold climate as well as hot climate, i.e. thick insulation in the walls and double or triple glassed windows. This will minimize the air leakage through the walls.

When the building is nearly air tight, the air quality will deteriorate quite quickly. To keep the air fresh, the whole air mass inside the house should be exchanged every two or three hours, This means that external air is taken from the outside and converted to the desired indoor temperature say 20 C, which requires energy for heating/cooling,

When the fresh air is blown into the house, a small overpressure will occur. There must be some (preferably controllable) leakage to let "spent" air escape to the outside world. In the cooling case, the vents should be close to the ceiling, letting warmed up air escape.

To further reduce heat ingress through radiation, some IR-reflective films can be used and the windows protected by external shades.

When calculating the amount of replacement air needed, one needs to consider the heat generated by humans (100 W/person) and heat generated by computers and other electronics.

To further reduce the energy demand in both heating and cooling. the escaping air should be routed through a heat exchanger.

"rules of thumb for residential fresh air requirements is 100 cfm for every 600 to 900 sq. ft. of living space"

900 ft^2 floor space w/ 8 ft ceiling = 7200 ft^3, so 100^3 per min = 1.2 hours per change. Whew, I doubt our winter homes are anywhere near that. It's probably more like 24 to 48 hours.

--
 Thanks, 
    - Win

A Heat Recovery Ventilation (HRV) system can recover from 70% to 85% of the heat in your exhaust air and bring fresh air into your home.

In the summer, the situation is reversed. You want to keep the hot outside air from entering your home, and still exhaust the old stale air. The HRV switches automatically so you don't have to do anything.

Ontario, Canada has made it mandantory for all new home construction. Huge energy savings in summer and winter.

How HRV (Heat Recovery Ventilation) Works

HRV, Heat Recovery Ventilator in Air-Tight House

Heat Recovery Efficiency

As the most energy-efficient HRV systems on the market, Comfosystems are up to 95% effective in recycling heat from the exhaust air to the supply air while promoting indoor air quality in tightly built homes.

I understand that, I'm questioning the numbers.

--
 Thanks, 
    - Win

What's your question? I provided links that define the efficiency you can achieve. In addition, the Ontario government now requires HRV systems to be installed in all new home comstruction. They work.

It should be noted that air leaks, particularly in the ceiling, need to be sealed. It is astounding how much heat loss can occur. Also, old two-story buildings are difficult or almost impossible to seal. The chimney effect is too powerful.

Losses can also occur if the input air is allowed to combine with the output air outside of the HRV.

An additional problem is to filter dirt, mold spores and pollen from the incoming air. Ordinary fabric filters have a very short life - perhaps three days at the most. By that time, mold sprores start growing on the fabric and increase the amount of spores leaving the filter instead of reducing it.

I have discovered that expanded aluminum microwave and stovetop metal filters can be very effective, especially if sprayed with a thin coating of mineral oil. The metal does not provide a medium for the spores to grow on, and the mineral oil does not support mold growth.

What is the obsession with mold spores? If the air outside is safe to breath, why is moving that air inside not safe to breath?

--

  Rick C. 

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Steve's point is to well seal the house and use heat exchangers to only bring in outside air that's been pre-warmed. I suppose that's where the mold vulnerability lies.

--
 Thanks, 
    - Win

he

e

ng

Sorry, how does that add up? If the air being brought in is from the outsi de, which is air that is perfectly safe, how is that a problem??? Seems to me the problem air is the stale air inside the house which is being exhaus ted to the outside, hopefully away from the intake.

All air has mold spores and other contaminants. Why does the outside air h ave to be cleaned before breathing on the inside of the house but not the o utside?

--

  Rick C. 

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Outside air is highly variable and often full of junk. Pollen can have a serious detrimental effect on those who are allergic. Residue and dust from car tires can absorb viruses and infect inhabitants of the house. Mold spores can have serious effects on those who are sensitive. A good filter system is needed to remove these contaminants before entering the house.

Most high MERV filters can handle pollen and road dirt, but can trap mold spores that start growing on the filter after a few days. Expanded aluminum filters coated with mineral oil can trap all these contaminants, but do not provide a medium for mold to grow on. The metal filters are also easy to clean and reusable.

So how do we survive outdoors?

--

  Rick C. 

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Inside the units and ducting there is a breeding environment for all sorts of mould and bacteria. A known problem in office buildings with lots of ventilation ducts.

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utside, which is air that is perfectly safe, how is that a problem??? Seem s to me the problem air is the stale air inside the house which is being ex hausted to the outside, hopefully away from the intake.

ir have to be cleaned before breathing on the inside of the house but not t he outside?

Still, what does that have to do with the outside air? If you install filt ers for the incoming air, is the house a sterile environment???

--

  Rick C. 

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BITD the litre was very slightly different from 1 decimetre cubed. My high school chemistry teacher was very clear about the difference, and quoted molarity etc. in moles/(dm)**3.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

That's what I was thinking, but I looked it up and they are exactly the sam e. Apparently the liter was originally defined in terms of the weight of w ater. Now it is defined as a cubic decimeter.

--

  Rick C. 

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On a suitable breeding surface, even with very clean air flowing along, you need only a few seedlings, to start the breeding process. And this surface, inside a duct or piece of equipment, never get cleaned. So this kind of pollution, once started, does not need bad air to attack your health. Maybe, installing UV lights inside might do something to stop the pollution.