How It Works: Passive Cooling

System Purpose.  Provide adequate cooling with minimum power

How It Works Summary.  Keep outside heat outside.  Keep sunlight outside.  Move inside heat to outside.   Minimize inside heat generation.   Move air inside house for evaporative cooling.

System Cost.  $200 for fans.    All other components are shared with other systems.   For example, wall insulation part of heating system.   

System Components

Keep outside heat outside.

Double-stud wall  with sandwiched R40 insulation.  R60 ceiling insulation.  R5 windows.

Keep windows closed while outside temperature is greater than inside.

Keep sunlight outside.

Majority of windows face south enabling effective blockage of sunlight by 2.5 foot overhang May through mid-August (while allowing passive solar heating in winter).    Exterior shade cloth blocks sunlight late August through early September. 

Porch over large east facing window blocks sunlight.

Two small windows face west and one east where overhangs are ineffective.  Interior shades provide some sunlight blockage.

Steel roof reflects sunlight away from attic.

Move inside heat to outside

When outside temperature falls below inside (night), heat rises up stairway to second floor where window fan exhausts heat outside and is displaced by cooler air entering open first floor windows.  This is ineffective on nights above 75F.    Most challenging for us is a series of such nights. 

Concrete slab-on-grade conducts heat into ground.    This is only partially effective since our slab is insulated to retain heat in winter.   Waiting for invention of “adjustable slab insulation”.

Minimize inside heat generation

Remember, inefficient is just another word for heater.  A 60% efficient refrigerator uses 40% of its electricity to heat your home, so you not only pay for electricity you don’t use, but you pay to get rid of the heat it creates.    

All our lights and appliances are very efficient and as such produce very little heat.  LED lights.  Sunfrost fridge in kitchen.   SunDanzer fridge and freezer in cellar.  Total simultaneous electrical draw for lights, freezer and 2 fridges averages 100 watts. 

Move inside air for evaporative cooling, i.e. use fans to wick sweat.

System Maintenance.  Open windows at night (if cooler outside).  Close windows in morning (when warmer outside).   Turn on 2^nd floor window fan, if needed.  Hang shade cloth over south facing windows in late August.  Remove in mid-September (or whenever the summer heat finally breaks).   

Report Card.   B    (See blog post for details).

Biggest Challenge.  Humidity.  Since passive cooling reduces temperature without removing moisture, the relative humidity actually rises inside the house.  Interior doors may swell and not close. 

Biggest success factor.  Summer attitude.   While 80F can feel hot (we hit 86F during last summer’s prolonged heat wave), we get used to it by enjoying ourselves outside on the porch.     A cool beverage really helps. 

The Connection.    We wanted a house that varied with the seasons, that says “yes, we are part of this ever-changing Land”.   

Recipe for Success

Nimble fingers flicking past card after 3x5 recipe card, Linda exclaimed.  “I could get rid of two-thirds of these.”   Seated on the kitchen bar stool---as I so often do to watch the master at her craft---I nodded knowingly.    She’d said a bagful in that one.  And we both knew it.  When your whole life feels condensed into a single phrase, what is there to do but stare?  Not only stare at the amazing she who’d said it, but at the movie now playing in my mind.    Actually, it was more like a trailer, a trailer for our life, our new life, turned upside down since 2004.

Incisors rip and tear.  Free-range chicken.    Whole Farm Coop.  Linda smiles.  “Guess I have to learn how to cook all over again.”

Omnivore’s Dilemma.  Purple sticky note.  If there’s a new right we need to establish, maybe this is the one:  the right, I mean, to look. 

CRV winding down pastoral County 26.  I glance over at Linda.  She looks rabid.  Crazed.  “Got to find a way to get those Dietz vegetables every week.”

Kitchen table.  Linda opens the CSA box.  Green.  Red.  We ooh and ah like Christmas.

Linda’s stained gospel.  The Splendid Table’s How to Eat Supper.  Each page silently whispers its mantra. “Local, seasonal ingredients sing together like tomatoes and basil.” 

And what title roles at the end of this trailer?   Pantry for a Revolution.    Trust Me, It’s Just a Meal.   Of course trailer’s don’t really tell you what the movies about.  Yet in our silence there in the kitchen, Linda and I did.   All those old 3x5 recipes that we’d never use again due to their ingredients.  Processed. Industrial.  Opaquely sourced.   New recipe cards took their place. 

And on the way to her well-stocked pantry, she’d found a new recipe for our life.   Linda’s bold move away from Industrial Organic toward transparent food---“do I know where this came from”---launched us off-the grid and into our new community-reliant life.  In retrospect its shocking how shocked we were by what we learned.  Our own…

Recipe for Success

Everything fulfilling happens up close and personal. 

The Top 5 Regrets of the Dying:  Be Myself, Work Less, See Friends, Express Feelings, Choose Happiness.

Discard the grid.  It’s impersonal and unfulfilling.

Food grid.  Power grid.  Entertainment grid.   Health care grid.  Education grid.  Trade grid.

Engage community.  It’s fun, rewarding and very, very tasty.

Friends.  Family.  School-mates.  Neighbors.  Volunteers.  Local food.  Sunlight.  Rain.  Trees.  Bees.  

  

Prairie Song

Yes, you’re going to hear me sing. So let’s get that out of the way.  What if not only I but the prairie could sing?   Sure,  May peepers split my ears.   August crickets strum day and night.  And sedge wren, he may not like to be seen, but he certainly doesn’t mind being heard.  So, I guess the problem is me.  I’m not sure of what the prairie sings? 

Does he sing of the days, years, centuries of glory, when grasslands rolled over every forest-rimmed hill?

Does she sing of the renewing flames, set so often by the peoples of the Land, the community of fire?

Does he sing of deep soil, the orgy of creatures beyond count, the ever-spreading mycorrhizal association-that vast inter-connecting web with no other name than life?

Does she sing of beauty to awaken the frosted soul, wave upon rolling wave of color?

Does he sing of thundering hooves, the grunt of bliss wallowing upon the abundance?

Does she sing of the great fall, so sudden, so complete?

Does he sing of lost loves---buffalo, bluestem, burrows---where are you, where have you gone?

Does she sing of plows, pavement and pastures of tortured grass?

Does he sing of the exhausted animal, lying on its side, suddenly opening an eye?

Does she sing of cream gentian, rising from the dying soil, shouting “I am prairie”.

Does he sing of hope?

Does she sing of our little prairie, a glimpse into what once was, a hint of former glory?

Does he sing of the dream, where the community of fire and the community of communities, become one?

Since I still failed to listen, my penance then is to sing my own.  Here’s the last two lines (This prairie song fills my heart) of Prairie Song written by my dear friend Doug Weatherhead for our Grand Opening Celebration.