InspectAPedia®   -   Search InspectApedia

Photograph of pink styrofoam insulating board (C) Daniel Friedman Climate Zones & BTU Requirements
Heating & Cooling BTUs by U.S. Climate Zone

Climate Zones of North America:

Find here: Climate Zone map for the U.S. giving heating and cooling zones and the definition of climate zones.

We include rules of thumb for estimating the necessary BTUs per square foot for cooling or heating a building in each climate zone.

We also include maximum cooling and mazimum heating requirements based on 30-year temperature averages provided by the U.S. government.

This article series defines Heat Loss, R-value, U-value, & K-Value measures of heating loss rate or insulation effectiveness and provides basic building insulation and heat loss guidelines including how to measure or calculate heat loss in a building.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

U.S. Climate Zones, Heating, Cooling BTUh Requirements

U.S. energy zone map - at InspectApedia.com

U.S. Heating Climate zones and Cooling Climate Zones are mapped using the same seven areas shown below, as of the IECC climate zone map provided by the U.S. Department of Energy.

The following map and heating and A/C cooling requirements for the various temperature and climate zones in the United States are adapted from the International Energy Conservation Code (IECC) and the U.S. Department of Energy (DOE).

Cooling BTUh or A/C size requirements by climate zone are given below at COOLING CLIMATE ZONE BTU REQUIREMENTS.

Heating BTUh or boiler/furnace size requirements by climate zone are given below at HEATING CLIMATE ZONE BTU REQUIREMENTS.

Source: IECC Climate Zone Map, U.S. Department of Energy (US DOE), retrieved 2018/06/21, original source: https://basc.pnnl.gov/images/iecc-climate-zone-map.

[Click to enlarge the map]

 

Typical Heating BTUh Requirements Per Square Foot

This table of required heating BTUs per square foot is based on the IECC climate zone map shown above.

Also see GAS BTUH, CUBIC FEET & ENERGY

Alternative HEATING BTU Requirements Zone Map

Below is a simplified 5 Climate Zone Map that can be used to make a rough estimate of your building's cooling requirements.

5-Climate Zone US Map Simplified - at InspectApedia.com

Below: the table gives Required Heating BTUs per Square Foot for each Climate Zone using the simplified climate zone map above.

Simplified Heating

BTU Requirements

Heating Zone Heating
BTUs / Sq. Ft.
Zone 1 30-35
Zone 2 35-40
Zone 3 40-45
Zone 4 45-50
Zone 5 50-60

...

U.S. 30-Year Average January Temperatures = peak heating need

Below: The 30-year average minimum temperatures reached in January across the U.S. between 1981 and 2010 - source: U.S. climate.gov retrieved 2021/06/08

30-Year average minimum temperature reached in January across the U.S. - at InspectApedia.com source: climate.gov

Below: The 30-year average temperature for the month of January across the U.S. between 1981 and 2010 - source: U.S. climate.gov retrieved 2021/06/08

30 year average temperature for January U.S. - at InspectApedia.com source climate.gov

 

Typical Cooling BTUh Requirements per Square Foot

This table of required cooling BTUs per square foot is based on a similar cooling zone map but that includes 8 cooling zones, described in the table.

Air Conditioner Heat Pump Tons Needed by Cooling Zone - ballpark3

Climate Zone1 Square Feet Required Cooling BTUs or A/C Tons Example Climate Zone Areas

Zone 1

Hottest

1 50-60 BTUh

Tons x 12,000 = BTUh

Tip of Florida

See IECC RESIDENTIAL PRESCRIPTIVE REQUIREMENTS below

600-900 sq.ft. 1.5 Tons / 18,000 BTUh
900-1200 2
1200 - 1500 2.5
1500 - 1800 3
Zone 2 1 45-50 BTUh

Most of Florida, Southern Texas, South Georgia

600-950 1.5
950-1250 2
1250 - 1550 2.5
1550 - 2000 3.7 - 4.7
2000 - 2600 4.7 - 6
2600 - 3500 6 to 8

Zone 3

Moderate

1 40-45 BTUh Central Texas, Central Georgia, South Carolina, Central GeorgiaCentral Texas, Central Georgia, South Carolina, Central Georgia, most of California
600 - 1000 1.5
1000 - 1300 2
1300 - 1600 2.5
1600 - 1900 3
1900-2500 3 Note 5
Zone 4 1 35-40 BTUh North Texas Panhandle, Washington State, Southern Michigan, Southern New York, Virginia, North Georgia
700 - 1050 1.5
1050 - 1350 2
1350 - 1600 2.5
1600 - 2000 3

Zone 5

Cool

1 30-35 BTUh Most of Washington State, Southern Michigan, Western New York, most of Pennsylvania, Northern California & Coastal, Boston area
700 - 1100 1.5
1100 - 1400 2
1400 - 1650 2.5
1650 - 2100 3
2100 - 2500 3.2 - 3.7
2500 - 3000 3.7 - 4
3000 - 3500 3.7 - 5.1

Zone 6

Cooler

  1 Northeast Washington State, Northern Michigan peninsula, Central New York North, Southern Wisconsin
citation needed 2
  2.5
  3

Zone 7

Cold

  1.5 Southern Minnesota, Most of Maine, Most of Northern Michigan, Northern Wisconsin
citation needed 2
  2.5
  3

Zone 8

Coldest

  1.5 Northern Minnesota, Northern Maine, Most of Northern Michigan, Northern Wisconsin
citation needed 2
  2.5

Notes to the table above

  1. IECC RESIDENTIAL PRESCRIPTIVE REQUIREMENTS, 2009 IECC International Energy Conservation Code defines eight climate zones in the U.S. and provides an interactive heating or cooling zone map, retrieved 2018/06/21, original source: https://energycode.pnl.gov/EnergyCodeReqs/
  2. U.S. Department of Energy, CLIMATE ZONES [PDF] retrieved 2018/06/21, original source: https://www.energy.gov/eere/buildings/climate-zones
  3. Watch out: Some HVACR equipment installers warn that just using a BTUh multiplier x square feet is not a very accurate way to estimate the heating or cooling load for your building.

    That's because the heat gain or loss will be very different in different rooms or areas of the building such as those facing the sun, those with more windows, etc.
  4. If you are looking for heating BTUh requirements

    see HEATING CLIMATE ZONE BTU REQUIREMENTS

    Also see DEGREE DAY HEATING DEGREE DAYS or COOLING DEGREE DAYS

  5. U.S. Energy Star Program Air Conditioner Sizing recommendations, retrieved 2019/09/27 original source: https://www.energystar.gov/index.cfm?c=roomac.pr_properly_sized.

    Watch out: this source does not relate cooling requirements to cooling zones in the U.S.
  6. Note that for "cold" climate zones 7 and 8 in the table above typical government energy sources don't give complete cooling load BTU requirement data.

The US DOE link above provides additional building specifications for each heating zone such as recommended insulation levels.

Alternative Cooling BTU Requirements Zone Map

Below is a simplified 5 Climate Zone Map for the U.S.

5-Climate Zone US Map Simplified - at InspectApedia.com

Below: the table gives Required Cooing or Air Conditioning BTUs per Square Foot for each Climate Zone using the simplified climate zone map above.

Simplified Cooling BTU Requirements
per 1000 Square Feet of Area
Cooling Capacity
Zone BTUs / Sq. Ft.
Zone 1 50-60 BTUh
Zone 2 45-50 BTUh
Zone 3 40-45 BTUh
Zone 4 35-40 BTUh
Zone 5 30-35 BTUh
General Rule of Thumb for room A/C units 20 BTUs

Notes to the table above

U.S. 30-Year Average July Temperatures = peak cooling need

Below: The 30-year average maximum temperatures reached in July across the U.S. between 1981 and 2010 - source: U.S. climate.gov retrieved 2021/06/08

30-Year average minimum temperature reached in January across the U.S. - at InspectApedia.com source: climate.gov

Below: The 30-year average temperature for the month of July across the U.S. between 1981 and 2010 - source: U.S. climate.gov retrieved 2021/06/08

30 year average temperature for January U.S. - at InspectApedia.com source climate.gov

 

What is the Relationship of Cooling Capacity and Dehumidification?

Tons of ice does not, however, explain an important factor in the comfort produced by air conditioning systems, reduction of indoor humidity - that is, removing water from indoor air. Cool air holds less water (in the form of water molecules or gaseous form of H2O) than warm air.

Think of the warmer air as having more space between the gas molecules for the water molecules to remain suspended.

When we cool the air, we in effect are squeezing the water molecules out of the air. When an air conditioner blows warm humid building air across an evaporator coil in the air handler unit, it is not only cooling the air, it is removing water from that air.

Both of these effects, cooler air and drier air, increase the comfort for building occupants.

One ton of cooling capacity equals 12,000 BTU's/hour of cooling capacity.

Also see

DEW POINT CALCULATION for WALLS

How do we measure cooling or heating efficiency: the relationship between BTUs and cooling or heating operating cost?

Note that the BTU rating of an air conditioner itself does not tell you how economically those tons of cooling capacity are being produced.

For the answer to that question see SEER RATINGS & OTHER DEFINITIONS for air conditioners and heat pumps.

 




ADVERTISEMENT





Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-06-08 by (mod) - How many BTU's are needed for Hennepin County Minnesota?

@Anonymous,

Hennepin County in our state (Minnesota) is considered in climate zone 7 or northern Hennepin possibly zone 8 - as given in the climate zone TABLE above. Or zones 6 & 7 using the older climate zone MAP.

Short answer: you need between 1.5 thousand and 3 thousand BTUs.

Detailed Answer: (We're working to improve the data below)

But from your question alone nobody can tell you how many BTUs you need to heat or cool your home.

To make a useful and credible estimate of the heating or cooling BTU requirements for your building you really need building specifics:

- its air-leakiness
- the R-value of insulation in the building's walls and ceilings
and to some extent also
- the shape of the building: a 2000 square foot building that is all on one level will have different heating and cooling requirements than one that is stacked up in four 500 sqft floors.

I'm embarrassed to say that our heating/cooling BTUs per Square Foot heating and cooling zone TABLE (shown above on this page) is fuzzy for zones 6 and 7 which include Minnesota - where we state
"popular heating zone maps for the U.S. do not follow the current DOE climate zone definitions that we accept here" for Minnesota and other parts of the northern U.S.

Using the IECC map (also on the page above) you're in zone 6 or northern MN zone 7


Or using the older IECC map that

So when we put this article together using the best data we could find, we're left with: for southern MN (zone 6)
Continuing:

Using a typical HEATING zone BTU calculator, for zone 6 you need about 55,000 BTUs per 1000 square feet of home area

Using a typical COOLING zone BTU calculator, for zone 6 you need about 22,000 BTUs per 1000 square foot of home area

Thank you for a helpful question

On 2021-06-08 by Anonymous

How many BTU's are needed for Hennepin County Minnesota?

On 2020-10-11 by (mod) - How many BTUS are recommended for Wallowa County Oregon

Tom

To determine how many BTUs you need for your home in Oregon choose heating zone 4 (or 5 if you prefer)
and then

take note of the number of square feet of your home; without square feet there is no reasonable estimate of BTUs that would make sense.

Watch out: Consider that homes vary widely in heat loss rate. In a poorly-sealed building, air leaks alone can overwhelm even very high-R insulated walls and ceilings.

That's why we must take all of these heating and cooling BTU requirements with a grain of salt (or a cube ice).

Consider also that with a radiant floor heating system in a 5-inch concrete slab, the success of that heating system depends enormously on just how the radiant heat system was installed.

If the tubing is too deep in the slab (not in the top 2") or if the slab was not properly and completely insulated from the ground, then the radiant heating system may not ever work successfully.

See RADIANT HEAT MISTAKES

On 2020-10-10 by Tom

How many BTUS are recommended for Wallowa County Oregon. Depending on the map I view it seems to fall into different zones. Zone 5 shows up a lot however. Im using Radiant floor heat in a 5 inch concrete slab.

Thanks very much

On 2019-09-27 by (mod) - BTU requirements for large houses

Thanks for asking Anon;

I have added some data for larger square-foot homes in the tables above.

You can also use the "BTUS per Square Foot" figure to calculate cooling or heating loads.

To make sense of these requirements it's important to note

and there are some more subtle factors that count such as

On 2019-09-26 by Anonymous

Your tonnage estimate chart only covers small houses. What about houses 2000 to 4000 sq ft

 


...

Continue reading at DEFINITION of HEATING, COOLING & INSULATION TERMS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

Suggested citation for this web page

CLIMATE ZONES for the U.S. at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to DEFINITIONS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Questions & answers or comments about the definitions of heating & cooling terms.

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification
when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Comment Form is loading comments...

Citations & References

In addition to any citations in the article above, a full list is available on request.



ADVERTISEMENT