We summarize the basic techniques used to save energy in a greenhouse and discuss the development of a new energy-saving pipe-framed greenhouse, similar to the type used on most small-scale farms in Japan. To enhance the thermal insulation performance of a pipe-framed greenhouse, a multi-layered thermal curtain was installed. As a result of our experiments, both the heating load and the heating oil consumption in the greenhouse with a multi-layered thermal curtain (M-house) were approximately 40% lower than those in the control greenhouse with a conventional thermal cover (C-house). Furthermore, the heating oil consumption was also reduced by approximately 60% in the M-house equipped with water heat storage, which stored solar energy in daytime and released heat to the greenhouse at night. This multi-layered thermal curtain is expected to gain recognition as the most effective energy-saving material available and immediate widespread use nationwide is expected. Another experiment was performed concerning the structural reinforcement of pipe-framed greenhouses. Pipe-framed greenhouses are usually constructed with single-arch pipes in Japan and there has been a recent increase in greenhouses collapsing due to strong winds. Accordingly, techniques to reinforce the structure of pipe-framed greenhouses were also developed.