Thread: Passive House Cooling

Originally Posted by watterinja

Fans, a/c, are 'active coolers'. You will need to broaden your views MM.

I know, but it didn't seem worth starting another thread.

Originally Posted by garyk

Every one knowes it is cheaper to heat water or air or whatever with a heat pump. With high effiency compressors and increased condenser area,,, very good. I see now two speed and even variable speed compressors now. For up to 20 SEER and up. COP of 9 and up.... WOW

The bottom line is cost ,,, cost ,,,, COST of installing and maintaining.

Go, GREEN

A few corrections.

1. COP
A COP at 50'C refrigerant saturation temperature, of 5 is thermodynamically possible - COP,hp ~ 9 is impossible at mid-range.

COP,hp ~ 8.62 at 30'C Tsat i.e. startup conditions.

These figures are using a scroll compressor, with high isentropic efficiency.

2. Cost
The purchase cost is the main obstacle, after that, the electrical cost is negligible. Maintenance of a well-manufactured AWHP is almost negligible. The system should have less maintenance cost than a conventional a/c system.

Originally Posted by garyk

I do not want a heated discussion here

no, it is about cooling

I stand corrected I was thinking of HSPF on a pump for heating and cooling. Which can go about 9.0. Heating season performance factor. And a lot of variables are here.. I am old so there...

I am a little confused if i remember correctly COP is KW supplyed as output. Compared to the KW input

For instance say your system is running 3.5 COP Then for each KW input you are producing 3.5KW output . (4.5KW output - 1KW work) = 3.5KW actual out put. (I THINK) If so it is no brainer to see how a pump for heating water or anything is cheaper than electric.

Also if i remember 1KW = apprx. 18K BTU -19K BTU. I will use 18,500 BTU / KW

If i am thinking about this right... ( please tell me if correct. and correct me )
If your unit is running say COP 3.5 then a 1KW input would deliver 64,750K BTU or 3.5KW. or about a 18,500 btu compressor

Question:

What is the COP of your unit.
How much in dollars is say a 3.5 KW output system or how do you typically size a house with your unit? Since you are storing the water for later use i assume. Lets say for a 30 gal. storage capacity. Again i am only guessing...

Send me a link to your site and specs.

Then i will decide....

Since i know nothing about heat pump water heaters i am interested.....

^ Hi Garyk,

PM me, & we can talk further.

COP,hp at 3.5 is on the low side of my designs, I typically expect more than 4 from a poor design & 5 from a decent optimised design.

So, you pay $1 into the machine & get $5 of heat energy - for a good machine. Like printing money.

Sorry 1KW = 3414BTU So a unit of COP 3.5 at 1KW= 11,949 BTU
or a 3,414 btu compressor... which is nothing....

Say input 5 KW at COP 3.5 = 59,745 BTU or a 17,070 BTU compressor.
This is better.... makkkkkkkk... OK Now i am interested more....

Just read an article mentionning a "hollow tiles" system that you install in your house had won a price. It was in french, good luck with google



But anyways, the best way to lower the temperature inside is to provide yourselves with SHADOW !
- green roof / insulation
- overhanging roof with air flow beneath
- shutters (mobile/fixed)
- trees...

Now it's even possible to simulate in 3D the exact shadow you receive from your environment (trees, houses, buildings...), for the location where you live, for everyday of the year.

Then you know exactly which part of the house to protect from direct sunshine, mostly around noon time for the hottest months. You can also calculate the angle of the sun rays you want to block when it's hot, and which angle to let go through when it's cold. I'm doing this for a villa in Chiang Rai and somebody who would like to use the sun to his advantage =D


That shadow calculation helps other systems such as the cool-air column (water/air), which termites and ants have been successfully using for millennia to set their hatcheries temperature to the exact degree they need.



There's a lot to be done in a house, systems acting in coroboration are more efficient than just one alone (even the latest 'super top ultra thing'). Better to think it up before building !

all true

when I designed my house I made sure which direction the sun came from.

Windows are not facing S or SW, in general

The walls are QCON, good insulation

There will be lots of shade to live in

Better to think it up before building !

An excellent suggestion...

Using swimming pool water? My pool water is 36c at the moment!.........
Drops to 24 ish in the cool season.........

Originally Posted by Airportwo

Using swimming pool water? My pool water is 36c at the moment!.........
Drops to 24 ish in the cool season.........

Sounds like you need some shade or A small cooling tower? But it would obviously use energy to run the fan. I have seen some local built ones that have no fan but I don't have any knowledge of how effective they are. I prefer to swim in water at 27, I don't like cold water.

here you go this American agrees with German thinking, that's led to quite explosive situations in the past, i thought i might add it for my worthless penny of thoughts

passivehouse.us • View topic - Cooling Passive houses

I agree with that link.
I had a cabin in cold country, but it would also get damn hot in summer days up where the air is thin and the sun came up at 0430 and set at 2130. in summer and in winter it came up at 1000 and set at 1430.
Walls were 7/16 Sheetrock,4 inches of Fiberglass blanket, 6 inches of wood, 2 inches of rigid at 15 Rs to the inch, and cedar ship lap siding.
The roof was Sheetrock, 4 inch FG blanket,1/2 inch plywood sheeting, 12 inches of rigid foam insulation and the aluminum roofing, in all 60 Rs of insulation and the snow stayed on the roof all winter. and all windows were triple glazed.

Originally Posted by blackgang

and all windows were triple glazed.

Double glazed units cost an arm and a leg. Can you imagine the cost of triple glazed units would be, plus the aggro in sourcing them>

Originally Posted by Marmite the Dog

Double glazed units cost an arm and a leg. Can you imagine the cost of triple glazed units would be,

There is a shop in sandpoint that makes them and the cost was more than I wanted to pay, I do remember that.
But when I acquired the cabin and 5 acres the end facing the creek, actually the front as the drive and parking were at the rear, was unfinished and it was sealed from above the kitchen/dining room windows and door out onto the deck with a heavy opaque plastic material, but was thermally OK but the noise level was terrible during breakup and spring water flows, it sounded like living in a bowling alley with the rocks bouncing along and banging together.
But I measured and made a plan for the windows I needed to finish the front and when it was done, it was very pretty, almost all glass with just the timbers and window framing, even the door was a thermal pane glass, and the next winter it was warmer in the house with a third the wood used, -40F and only used 1 cord of wood to heat it and during breakup, it was quiet in the house, and I got to see it too.
I was setting out on the deck in the sun reading, and could hear a train rumbling sound, well we were about 20 miles thru the forest and over mountains to the train tracks, so was strange, but the sound got louder and then it sounded up canyon, not down,
there was a fork in the creek out in the canyon in front of the house and the creek ran in front about 15 feet from where I was setting and also a branch ran around on the other side of a wooded island type piece of lane in front of me and went around to my right and came almost straight back to where I was setting and them turned at my property line and went down canyon.
So I was setting right in the middle of this action, I notice the water rise up over the ice and snow in front of me and was kind of muddy brown color, then up the canyon on the other side of that forested Island here came the breakup, Ice chunks and trees and water and all kinds of shit was coming roaring down stream, rolling and bucking and whole trees it had torn out and huge chunks of ice and it was 50 or more feet high and going 50 miles an hour and such noise as I have never heard before, around the bend and straight at me and then turned again and down stream it went, lasted for a good 30 minutes before is slowed down and shit quit coming down stream,, I never will forget that day.

Originally Posted by DrAndy

you can make sure that your window frames have the rebates to fit the three glass panes correctly

For sure, you can have wooden ones made, but I was thinking about aluminium or uPVC units.

Is there a reason why traditional Thai houses are built up off the ground - on stilts?

yes

they are cooler, cleaner, you get less pests coming in, and you can keep the pigs under

maybe helps during the wet season too

Originally Posted by Marmite the Dog

aluminium or uPVC units.

The ones we used were PVC, aluminim is not to good when it gets really cold as they tend to sweat and ice up.

Originally Posted by Marmite the Dog

Originally Posted by DrAndy

you can make sure that your window frames have the rebates to fit the three glass panes correctly

For sure, you can have wooden ones made, but I was thinking about aluminium or uPVC units.

wooden ones are much better, and look better too

PVC may be Ok; are they sun-proof?

Originally Posted by DrAndy

PVC may be Ok; are they sun-proof?

The ones used over here are supposed to be.

prob not then

wood every time