Windows are more expensive than walls, including labor. They and their
framing insulate poorly, and they can leak rain and bugs and burglars
The 2006 International Residential Code says:
Section R303 Light, ventilation and heating
... All habitable rooms shall have an aggregate glazing area of
not less than 8% of the floor area.
BUT we have exceptions :-)
1. The glazed area need not be openable where the opening is not required
by section R310 and an approved mechanical ventilation system capable of
producing 0.35 air changes per hour is installed or a whole house fan
is installed capable of supplying outdoor air of 15 cfm per occupant...
2. The glazed areas need not be installed in rooms where Exception 1
is satisfied and artificial light is provided capable of producing
an average illumination of 6 footcandles (65 lux) over the area of
the room at a height of 30" above the floor level.
Section R310 requires:
Emergency escape and rescue openings with a sill height of not more than
44" above the floor... with a minimum net clear opening of 5.7 ft^2...
So the BOCA code requirement for 8% of the floor space as windows can be
eliminated. One ICC code-interpreter confirmed this. Hooray :-) We only need
about 2% of the floor area for sunlighting, but why not replace windows with
fluorescent lights and insulated doors and ventilation systems and outdoor
cameras and flat screen TVs on the walls?
We might use $9.99 web cameras and $124.99 20" flat screens and consider
the installation and operating costs, as well as the price in the box,
and switch to a Chinese feed when it's dark outside.
Have you calculated the costs?
Let's say you want to replicate the image from a 6x4 foot window.
This is a modest sized window. Many folks prefer them larger.
So, what resolution? Most LCD computer monitors have around a
.28mm dot pitch, or a resolution of 3.5 dots/mm or 88 dots/inch.
A 6 foot wide window would then require (88x12x6) 6336 dots across
and (88x12x4) 4224 dots down. (Dots=pixels)
Assuming we'll accept a matrix of 20" LCD monitors, then a sample
monitor (ACER AL2017BMD $250) measures 17.8"W x 19.4"H so 4 across
and 3 down for 12 monitors costing $3,000. These particular ones
have a screen resolution of 1400 x 1050 so combined they'll amount
to 5600x3150 with breaks where the frames are. This is probably
acceptable resolution as long as no one wants to stand too close.
The $150 20" LCD's probably refer to TV's which have a resolution
around 640x480 (VGA). I find this resolution isn't even enough to
watch TV, let alone replicate the much finer details of the real
world through a window.
The resolution of a $9.99 web camera is 640x480. I would, offhand,
consider this number way too low to provide 1400x1050 or 5600x3150.
Let's say we wanted to use web cameras though. How many? You would
need a matrix of 2x2 (4 cameras) to provide even close to the image
resolution of one single screen and 12 times that for the entire
array. Still 48 cameras at $10 each is only $480.
If one wanted to go with a single camera then they would need at
least the 5600x3150 resolution and maybe more to account for the
parts of the image blocked by the LCD frames. HD video cameras
won't produce this resolution but a still image camera might.
5600x31500 amounts to 17.6 Megapixels. Dell sells a Cannon Camera
EOS-1DS Mark II for $7,200 with a 16 Megapixel resolution. I think
the lens is extra.
You won't get continuous live video from these cameras at these
resolutions so they wouldn't exactly compare to the experience of
a real window.
Let's assume you'll need at least $1,000 in computer equipment to
run 12 monitors and 48 video cameras (or one or two still cameras).
The cheapest version of this would run $3,000 monitors, $480 cameras,
$1,000 CPU, $4,450 with no upward limit on cost if you want better.
How much does a 6x4 foot double pane window cost? Oddly enough, I
couldn't easily find anyone who gives numbers on the web. Perhaps
I wasn't using the right search terms but they all seemed to want
to give me a free in-house estimate. Weird. Still, does a single
window cost more than $4,500? I don't think so. I know of one fellow
who replaced all the windows in his home for less than $10,000 and
he had more than 2 windows.
How much does it cost to provide the heat that is lost through one
6x4 foot window over the course of, say, 30 years, compared against
an insulated wall? Somehow I don't think this amounts to thousands
of dollars either.
So, windows are more economical and you don't have to replace their
backlights every 30,000 hours of use.
Nick was saying that windows are not as good at keeping heat out/in
a structure as walls. This is not in doubt. Even double pane windows
are only typically rated in the R3 to R6 range while walls typically
start around R16 and go up from there.
Nick further proposes that people could use video cameras outside
and TV screens inside to take the place of windows. This would let
them look outside without an actual, real, window.
I then proceeded to put some numbers to this video-window proposal
to show that it's not economical at this time.
The following is an example of what we are talking about.
That depends on the resolution. I proposed $135 windows. I'd probably
notice that the view doesn't change when I walk around the room, but
a few "windows" like this might be nice for non-critical views.
PA has about 5500 (F) HDD/year, so a square foot of R30 wall would
lose 24hx5500x1ft^2/R30 = 4400 Btu of heat per winter worth 1.3 cents
at 10 cents/kWh. A square foot of R3 window would lose about 13 cents,
or maybe twice that, counting the framing and air leakage. A 2400 ft^2
house with 8% of the floorspace (192 ft^2) as non-south windows might
lose $50/year through the windows.
If each of 32 2'x3' windows costs $100, and framing and installation
double that, a window house might cost $6400-4320 = $2080 more than
a house with 32 20" flat screens with VGA resolution.
Bill Gates allegedly has a house with something like this on the walls,
as well as windows.
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