Insulation Levels & Climate Zones

Different rooms or parts or the house and different climates may involve different recommended amounts of insulation... You should take into account your particular climate zone, the parts of the house you want to insulate and the insulating R-Value of the material you should apply...

Climate and Insulation

The main goal of insulation in cold climates is to reduce heat losses (to reduce the summer heat is a secondary goal), while in tropical humid climates, the insulation main goal is to reduce heat gains (a secondary goal is to keep cooled air inside).

But there are other mixed situations. In some warm climates and hot dry climates with cold winters, the insulation goal will be to reduce both heat losses and heat gains.

Besides, as expected, recommended insulation levels vary a lot with the part of the house. Roof, ceiling, walls, floors and basements have different insulation R-value needs...

Recommended R-Values in cold and mix climates

The recommended values shown below (from the American Energy Star) for American climates, can be applied to other states worldwide (see also Recommended R-values in hot and tropical climates). Just pay attention to the the sub-types of climate considered in the table (for hot and tropical climates, see climate. The values are expressed in the non-SI rating system (conversion relation: 1 (SI)/5,67 (non SI); see, for more details on this issue: R-Values).

Recommended Insulation R-Values for Existing Houses
TYPE OF CLIMATE

TYPE OF HEATING SYSTEM b

 LEVELS OF INSULATION
Ceiling Wood-frame wall Floor Basement/ Crawl space walls d
Warm with cooling and minimal heating requirements (i.e., FL & HI; coastal CA; southeast TX; southern LA, AR, MS, AL & GA). gas/oil or heat pump R-22 to R-38 R-11 to R-13 R-11 to R-13 R-11 to R-19
         
electric resistance R-38 to R-49 R-13 to R-25 R-13 to R-19 R-11 to R-19
         
Mixed with moderate heating and cooling requirements (i.e., VA, WV, KY, MO, NE, OK, OR, WA & ID; southern IN, KS, NM & AZ; northern LA, AR, MS, AL & GA; inland CA & western NV). gas/oil or heat pump R-38 R-11 to R-22c R-13 TO R-25 R-11 to R-19
         
electric resistance   R-11 to R-26c R-25 R-11 to R-19
         
Cold (i.e., PA, NY, New England, northern Midwest, Great Lakes area, mountainous area (e.g., CO, WV, UT, etc.)). gas/oil R-38 to R-49 R-11 to R-22c R-25 R-11 to R-19
         
heat pump or electric resistance R-49 R-11 to R-28c R-25 R-13 to R-19
         
b. Insulation is also effective at reducing cooling bills. These levels assume your house has electric air-conditioning.
c. R-values may be achieved through a combination of cavity insulation and rigid board insulation and are for insulation only (not whole wall).
d. Do not insulation crawl space walls if crawl space is wet or ventilated with outdoor air.

R-Values in hot, temperate warm and tropical climates

The recommended values shown below (from the Australian Government Greenhouse) for Australian climates, are also valid to temperate-warm and tropical climates in most other countries. Be aware with those values: pay attention to the 5,67 factor for a non-SI rating (see, for more details on this issue: R-Values).

Pay also attention to the meaning of the zero value, in the table. That zero doesn't mean that no insulation is needed. It just means that insulation to reduce heat loss may not be needed and can cause overheating in houses without a proper sun control. In these cases, you should use a proper type of insulation: one that prevents heat gains without restricting heat losses. In technical terms: you should use insulation with high down r-values and low up r-values.

Note: In hot climates insulation should prevent heat gains without restricting heat losses, to avoid overheating. To get it, people use reflective insulation materials, with high down r-value and a low up r-value. Up R values - or winter R-values - describe resistance to heat flow upwards (heat escaping into outdoors through roofs or walls…); Down R – or summer R-values - describe resistance to heat flow downwards (heat entering into the house through roofs or walls…).  

CLIMATE TYPE AND RECOMMENDED INSULATION LEVELS
EXAMPLE OF LOCATIONS (material or system R values)
  ROOF/CEILING WALL
Cool Temperate & Alpine
Melbourne, Vic 3.0 x 5,67 1.5 x 5,67
Canberra, ACT 3.5 x 5,67 1.5 - 2.0 x 5,67
Hobart, Tas 3.5 x 5,67 1.5 - 2.0 x 5,67
Mt Gambier, SA 3.0 x 5,67 1.5 - 2.0 x 5,67
Ballarat, Vic 3.5 x 5,67 1.5 - 2.0 x 5,67
Thredbo, NSW 4.0 x 5,67 1.5 - 2.0 x 5,67
Hot Humid & Hot Dry
Darwin, NT 0* -4.0 x 5,67 0* - 2,0 x 5,67
Cairns, Qld 0* -3.5 x 5,67 0* - 1,5 x 5,67
Broome, WA 0* -4.0 x 5,67 0* - 2,0 x 5,67
Marble Bar, WA 0* -4.0 x 5,67 0* - 2,0 x 5,67
Mt Isa, QLD 0* -4.0 x 5,67 0* - 2,0x 5,67
Tennant Creek, NT 0* -4.0 x 5,67 0* - 2,0x 5,67
Townsville, QLD 0* -3.5 x 5,67 0* -1,5 x 5,67
Temperate & Warm Humid
Brisbane, QLD 1.5 - 2.5 x 5,67 1.0 x 5,67
Perth, WA 1.5 - 3.0 x 5,67 1.5 x 5,67
Alice Springs, NT 1.5 - 4.0 x 5,67 1.5 - 2.0 x 5,67
Bourke, NSW 1.5 - 4.0 x 5,67 1.5 - 2.0 x 5,67
Sydney, NSW 1.5 - 3.0 x 5,67 1.5 x 5,67
Adelaide, SA 2.0 - 3.0 x 5,67 1.5 x 5,67
Katoomba, NSW 4.0 x 5,67 1.5 - 2.0 x 5,67

Reflective insulation (Radiant barriers)

Reflective insulation - mainly applied in roofs with the goal of blocking the sun's heat - is a very specific case. While highly advantageous in hot-warm climates, reflective insulation is often dispensable in colder climates.

See: Reflective Insulation.

See also: