The Metro board postponed for at least two weeks yesterday the $10.8 million purchase of 115 new buses because the board's District of Columbia representatives decided the buses should have windows that open and close and they don't come that way.

The issue surfaced at the as minute in what had been a routine bidding process. General Motors Corporation was the low bidder for the buses and the board must award the contract by Jan. 20 or restart the bidding process. Such procedures almost invariably result in higher second bids.

"Air conditioning doesn't always work," D.C. board member Jerry A. Moore noted when he was told that was the only way buses would be cooled during Washington's fierce summers.

The GMC bus is called an Advanced Design Bus." It has a backup air conditioning and ventilation system and was designed in accord with standardized federal-government-approved specifications. The federal government picks up 80 percent of the cost of new buses.

Moore was asked why the sealed window issue is just surfacing when the Metro board had approved the specifications weeks ago when it sought bids. "I don't know that it's ever too late to ask for information," Moore said.

"The problem is one of passenger comfort," said D.C. transportation director Douglas N. Schneider. "Will the bus be suitable to the needs that we have?" He complained about the ventilation in his office, which is located in a sealed building with unopenable windows.

Cleatus Barnett, of Montgomery County, noted that on existing buses passengers often open windows and hang their arms out, making the air conditioning inefficient even if it is working.

The board actually voted yesterday to reject the bid then voted to reconsider and defer final action. "I want to know whether this is a negotiable point," Moore said.

A spokesman for General Motors said yesterday that the advanced design bus has only one kind of window - and it is sealed. Windows that open "are not an option," he said.

In other actions yesterday the board established a six-member committee to develop a new agreement for completing the 100 mile Metro system. The agreement would take the form of a binding contract on local and state jurisdictions to raise construction money. Such a contract, and the money, are necessary to match available federal construction funds. Sixty of Metro's 100 miles are funded.

The board and the Metro staff also gave a standing ovation to outgoing chairman Joseph S. Wholey, who is retiring from the Arlington County Board and thus the Metro board as well. Moore will the next board chairman, a position that rotates among the three major jurisdictions.