How many office buildings are there in the United States or where
would I be able to find this information?

Depending on how you define "office building," the estimates vary widely.

The most conservative estimate comes from preliminary data of the 2003
Commercial Buildings Energy Consumption Survey, which gives 824,000 as
the number of buildings in the United States whose "principal building
activity" is categorized as "office":

                     Number of 
                     Buildings 
                     (thousand)
          
All Buildings          4,859         

Principal Building Activity
-------------------------------    
Education                386  
Food Sales               226 
Food Service             297  
Health Care              129  
Lodging                  141  
Mercantile               657 
Office                   824 
Public Assembly          276 
Public Order and Safety   71 
Religious Worship        372  
Service                  622 
Warehouse and Storage    597 
Other                     79 
Vacant                   182 

Source: Energy Information Administration
2003 Commercial Buildings Energy Consumption Survey 

Energy Information Administration Commercial Buildings Home Pages 
http://www.eia.doe.gov/emeu/cbecs/cbecs2003/introduction.html

Other estimates seem to be considering all commercial buildings as
"office buildings," and thus come up with much higher figures:

"According to Jordan Glazov, president of U.S. RealTel Inc. in a
KnowledgeSpace interview, there are more than 4.6 million office
buildings in the United States..."

Houston Business Journal
http://houston.bizjournals.com/houston/stories/2000/01/31/focus3.html

"In the U.S., $200 billion is spent each year to heat, cool, light and
run 95 million homes and 5 million office buildings."

MSNBC News: Tapping into other technologies
http://msnbc.msn.com/id/3072277/

Google search strategy:

Google Web Search: "million office buildings"
://www.google.com/search?hl=en&q=%22million+office+buildings%22

Google Web Search: "commercial buildings" + "census"
://www.google.com/search?hl=en&q=%22commercial+buildings%22+census

I hope this is helpful. If anything is unclear, please request
clarification; I'll gladly offer further assistance before you rate my
answer.

Best regards,
pinkfreud

---

Clarification of Answer by pinkfreud-ga on 10 Nov 2004 14:35 PST

Here's an estimate that is lower than the one published in the EIA's
Commercial Buildings Energy Consumption Survey. However, no source for
this figure is cited:

"There were over 730,000 office buildings in the U.S with 11.8 billion
square feet of office space."

GEG Solutions: Office Buildings
http://www.gegsolutions.com/Literature_Files/Industry_Sheets/Office.pdf