既有建筑节能改造是建筑节能工程的一个重要组成部分。北京市既有建筑的节能改造工作时间紧迫、任务繁重。为此,对北京既有建筑节能改造面临的困难和问题，对既有建筑节能改造的对策和途径进行了深入的分析和探讨。

Project of energy efficiency refurbishment for the existing buildings is a very important part of the construction industry, which is really a time-pressing and task-heavy project in Beijing. This paper analyzes the difficulties and problems faced by Beijing City in energy efficiency refurbishment for the existing buildings, and discusses the methods and solution to retrofit the existing buildings in energy saving.