ITERIOR DESIGN ELEMENTS

D.

I

\

Center for Building

Technology

National Engineering

Laboratory

National Bureau of

Standards

Washington, D.C. 20234

JiATIONAL BUREAU

I

rtical

'eave

14. Interior

Coverings

Roll shades, inside

storm sash, heavy

drapery, shutters

15. Integrated

Lighting

Fixture circuiting,

task lighting, lightsensing automatic

controls

16. Interior

Mass

Masonry, concrete,

stone, water

Of STANDARDS

LIBRARY

APR 1 7 1981

not

EXAMPLES

no, >a /5

Solid weatherstripped shutters

improve airtightness

A. Air Tightness

Water container

seams critical.

Also see "M"

below

B. Water Tightness

DESIGN FOR BETTER WINDOW PERFORMANCE

EXTERIOR DESIGN ELEMENTS

j U.S. DEPARTMENT OF COMMERCE

| Philip M. Klutznick, Secretary

| luiher H. Hodges. Jr.. Deputy Secretary

| Jordan J. Baruch.

Assistant Secrelary lor Productivity, Technology and Innovation

J NATIONAL BUREAU OF

I STANDARDS

I Ernest Ambler, Director

EXAMPLES

0.1 *

1. Landscaping

Shade trees and

windbreaks consisting ol hedges,

tree lines, fences

2. Shades

Sun screens,

louvers, awnings,

architectural projections

3. Coverings

Roll blinds, shutters, storm sash

4. Sun

Orientation

South-tacing windows .

FRAME DESIGN ELEMENTS

m -J

5. Insulated Frames

Wood or metal

with a thermal break

6. Opening Type

Casement, awning, double-hung,

sliding, jalousie, pivoting and

hopper

7. Weatherstrip

Pile, vinyl, foam,

brass, or copper

Hardware

Latches, operating

devices, locks, and hinges

GLAZING DESIGN ELEMENTS

9. Multi Glazing

Fused-edge or

organically sealed

insulating glass

10. Reflective Glazing

Reflective coated

glass or films

11. Plastic Glazing

Polycarbonate

(PC) or acrylic (AC) sheet

12. Glass Block

Hollow masonry

units of glass

100

U57

no, 575 1980

Reference!

NBS

Publi • cations

/ INTERIOR DESIGN ELEMENTS

TO

4 2

13. Interior Shading

Venetian or vertical blinds, open-weave

drapery

14. Interior Coverings

Roll shades, inside storm sash, heavy

drapery, shutters

15. Integrated

Lighting

Fixture circuiting, task lighting, light- sensing automatic

controls

16. Interior Mass

Masonry, concrete,

stone, water

Center for Building Technology

National Engineering

Laboratory

National Bureau of Standards Washington. D.C. 20234 I BATION1L BVHEAU

Of BTANDABDa

LIBBAST APR 1 7 1981

EXAMPLES

I A. Air Tightness

1 B. Water Tightness

Reduced potential

for water or air leakage to extent

that windbreak

shields the window,

reducing wind and

water velocity

Reduced potential for water or air leakage

to the extent the device shields the window.

Provide positive drainage for trapped water. Lack ol drainage and freezing can increase

air and water leakage

|C. Natural

Ventilation

A windbreak may

alter summer wind

direction and in- crease or decrease

local velocity

May impede natural ventilation. Even insect screen reduces air flow by 50%

May or may not coincide with optimum

orientation for summer prevailing breezes vs. winter wind. Correct

conflicting orientation requirements by

using other design elements such as nd scocps Or

planting

Are as important as insulating value. Per- formance varies greatly with quality of win- dow and type of operation. Hinged win- dows tend to be more airtight than vert, or horiz. sliding units. Excellent to minimum

performance: 0.1 to 0.5 cfm per crack foot at26mphwind. ASTM e283-73 test Note: Specify mfgr's production average. Provide

positive drainage and keep weeps clear. Hopper, awning or jalousie provide some

rain protection when open. ASTM E-331

water penetration test used for evaluation

Since tightness degrades with use, ease of replacement

essential. Pile type

w/fin desirable for sliding units; use compression or spring type for hinged units

By cam action hardware can force

tight closure of sash. Improper

design can twist frame causing

increased air and

water infiltration Drain sill channels

well to prevent

failure of organic edge seal of glass

Large thermal movement requires

large edge

clearance, deep

containment, gaskets or flexible sealants

Seal at joint between adjacent

construction and

glass block

important. Expansion can be

great

D. Insulation

Windbreaks and shades will reduce rate of erosion of insulating layer of air at surface

of glass to extent window is shielded from wind

| E. Solar Admittance

Trees and tall hedges can reduce

insulation

I F. Daylighting

Landscaping

elements may

block daylight

if in overgrown

condition

Ventilate space

between window

and shade at top and bottom. Re- move or adjusl to admit winter sun

Dead air space

between covering and window

insulates. More

airtight coverings

better

Reduced solar gain according to shading coefficienl Adjust to admit

winter sun

Sol-air temperature

useful concept. SeeASHRAE

Handbook of Fundamentals, Locate spaces to receive winter sun

during time of occupancy

Should be

specified with

multiple glazing in moderate and

severe climates

Direction and axis

of opening directs

airflow. Openable

free area critical

May limit how

window opens thus

affecting quantity and quality of ventilation

Operable vents

available same

size as block module

Single glass U-value: (winter) = 1 .10 btu/ft-h' f

Storm = 0.5 Double = 0.6 {W space)l.R. refl. - 0.7

Sol. refl - 0.9 Polycarbonate or

acrylic = 1 06

12" sq. face

1 cavity = 0.52

2 cavity = 0.44

Excessive widths of sash and frame members reduce solar gain. Use net glazing areas for calculations

Ya " glass: shading coeff. (sc) = 1 .0. % sol transmission (sol) = 87

(Yb + Ye) clear: 0.89 % sol = 69

Low example

sc = 0.38 % sol - 1

= 0.98 AC

= 0.98 PC

= 85 AC

= 82 PC

High example

sc = 0.65 % sol = 60

overdone, shading can necessilate ex- pensive electric lighting. Ideally, device

should reflect light to ceiling for maximum

depth of daylight penetration into room

Intensive solar exposure for winter heating may cause

glare. Provide

control using design elements

Frame interior faces should be a light color

to reduce contrast glare. Position window

head near ceiling for maximum room depth

of daylight penetration

Ya " glass: % visible transmission (vis) = 90

Low example % vis = 15 % vis - 92 AC

= 88 PC

High example % vis = 75

Negligible Solid weatherstripped shutters improve air- tightness A. Air Tightness

Concurrent

shading and

ventilation desirable

Closed mode may

preclude natural

ventilation

Mtnimal if free movement ol room

air between device and window

Depends on air- tightness of covering and

tightness of edge

fit

Shading coeff. Ye"gl = 1.0

Ven. Blind =0.6* Roll shade =0 3' Open weave Tight weave

curtains = 08* curtains = 0.3* 'Closed 'Closed

Experimental

reflective Venetian

blind. Contact:

1 Oak Ridge Lab

2 Lawrence!

Berkeley liab

Can be effective

for complete

black-out

Daylight sensing

control operalion

on/off or continuous dimming

Water container seams critical. Also see "M"

below

B. Water Tightness

Mass cooled by

night air can

provide daytime

cooling

Daylime heat loss reduced because mass absorbs heat, reducing over- heating of space

Solar heat absorbed by mass

permits greater glass area, w/o

overheating

Dark color for solar absorption reduces room

daylighting

C. Natural

Ventilation

O. Insulation

E. Solar Admittance

F. Daylighting

|G. Visual Separation

Opportunity to provide privacy as desiredSome types as seen from outside are opaque during day but transparent at night Tend to distort color rendition of view and correct sense of time

Scratches can

detract from

quality of view out

View out/in

distorted or entirely obscured depending on lype

See extenor'shading and coverings Mass" walls can

provide complete

visual separation and passive

solar heat

G. Visual Separation

| H. Acoustical

Isolation

Principal benefit

is psychological. Provides minimal

actual sound

isolation

Decreases as

distance of noise ncreases. Over- hangs can reflect noise to the window

Can be effective

if airtight and

materials not same

thickness or

density

Airtightness critical to "sound tightness" Y>" cavity = 32

6" cavity = 40

e" single glass sound transmission loss (db)

'/> " thick = 29 AC

= 31 PC

Negligible

Stand blk. = 38

Solid blk. = 45

Depends on air- lightness as in "D"

above

No lighting system hum with daylight Mass provides the best acoustical

solation if no

penetrations

H. Acoustical

Isolation

I. Safety

Could alter circulation patterns to keep people away

from windows

Projections within 7 ft. of grade may

be hazardous to pedestrians

Can reduce fre- quency or severity

of breakagerelated accidents

Windows

projecting in or out can be hazardous depending on

location

Should not require excessive force to open or close windowCan limit opening dimensions to prevent children from falling out

Insulating glass

eliminates hazard

of installing/ removing storm sash

May cause

disorienting glare

to pedestrians/

drivers

Reduced probability of breakage-related

accidents May help prevent direct contact with <

in impact situations

Check allowable

floor loading, caulion in disposal

of toxic additives

I. Safety

| J. Access/

Egress

Must be located so as not to block emergency access

or egress

Must be easily removable from inside for emergency exiting through windows used

for egress. Must not reduce area or dimension below minimum required

Must not interfere with easy exitingTypical exit window: 5.7 sq. ft. min. area, 21" min. dimension, 44" max. sill heightShould not inhibit the easy opening

of windows used

for emergency

egress

Should facilitate rapid opening for emergency egress

Greater hazard to enter/exit through broken-out window

Avoid creating

reflections that could confuse emergency exiting

Pop out gaskeling may be desirable

(or egress through

fixed units

K. Ease Of Operation

Accumulated

organic debris may reduce ease

of operation

Interior operation of exterior devices desirable to meet changing exterior conditions or interior requirements

Must resist forces

of operation and

prevent binding of sash

Height affects ease

of operation of

different window

types

See "I" above Gear reduction or leverage can

increase ease of operation

Increased weight makes operation more difficult due

to inertia, friction

Requires no management by

the occupant

Decreased weight makes operation

easier

Essentially inpenetrable for emergency egress

Should not hide windows, and thereby re- duce the likelihood of their use lor emer- gency egress, nor impede any quick- opening qualities

J. Access/

Egress

Due to easy accessibility interior coverings

are more likely to be used No occupanl

operation required

with automatic

controls

No operation

required K. Ease Of

Operation

, L. Forced Entry Resistance

May provide cover

for intruders or

act as partial barrier

May deter intruders depending on ease of removal or noise from breakage. Locked

shutters or roll blinds very etfective

Rigidity of frame and sash important

to resist prying

No exposed

removable hinges. Sash or glass should be removable from

inside only

Soft weatherstripping can

permit insertion of wire to unlock window

Function, quality placement, and

anchorage critical to security

See "J" above Impedes outside daytime

surveillance

Ye" glass breaks when V* lb. steel ball dropped on a 12" sq. Sample at height of 24" AC = 72" Stand blk, = 200"

lo 1000" Solid = marred at PC = 1000" 320"

Can prevenl

burglar's surveillance of interior

M. Durability/ Maintenance

Require pruning,

feeding, watering

(plants), painting (fences)

Must withstand wind, rain, ice, and intense

solar radiation. May require seasonal re moval Some are self storing—e.g., roller awnings Detail installation to avoid sta ing adjacent materials

Avoid use of materials whose

appearance is diminished by

fading

Thermal break

material must be UV stable or protected from

sunlight

The more movable

parts the greater

the possible need

for maintenance

Must be detailed to permit periodic replacement

Simple is beautiful and makes

economic sense

Durability of edge

seal of insulating glazing critical

Scratch resistance important Caution

in cleaning

Easily scratched. May increase frequency of replacement is

Can discourage

penetration if locked closed

Can be integraled

with security system to turn on

lights upon

intrusion

L. Forced Entry Resistance

Very durable but

if damaged,

replacement

difficult

The need for periodic cleaning makes ease

ol removal desirable

Daylight use

increases lamp

life if switching nfrequent

Water may requir antifreeze, rust nhibilor, or algaecide M. Durability/ Maintenance

NBS Special Publication SP 575