When designing the building equipments, the capacity and the material of the equipments are the main concerns along with the budget, and the design is determined so that it is most suitable for a certain point of condition which is required for the indoor work environment and the equipments. Also at the construction site, preventing mistakes on the specifications and the numbers is considered important, but not much attention is paid to how the quality of construction affects the system. Especially when renovation is repeated, people often overlook the importance of the overall system efficiency because they are focused on responding to specific problems. After the completion of construction, the functionality of building equiments as a system is important, and therefore, examining the equipments only at the completion is not sufficient.

The requirements for indoor environment are constantly changing in response to the external and internal load, and accordingly, the equipment system is also greatly influenced by the equipments and system capacity, frequency of use, operating hours, age of the machines, and maintenance. As a result, the system function fluctuates and causes energy losses and reduced life expectancy of the equipments.

The lives of building equimpents can be stretched just like what we do with human body - prevent illness and accidents and stay well by daily maintenance and periodic diagnosis. New drugs and treatments should be adopted as an improvemt in technology. With that, we can realize the harmony between human capabilities and machines.

Appropriate Equipment Capacity
The capacity and size of equipments are determined so that they can cover the peak time demand in the indoor environment. However, the time period when the peak demand is reached is very short, therefore, the equipment capacity that meets peak demand is too large for the most part of the year and inefficient. For example, our study shows that only 60% or less of the capacity is used for 80% of the time in a year.
If we can respond to the building's operating rate and weather condition (temperature, wind speed, humidity and sunlight) withoug excess of deficiency for 365 days of the year, that will be the most energy efficient building equipment.

Floating Condition/Zoning
The demand side requirements are not constant, but floating because of the change in human comfort level during work and also machines and equipments. It may be appropriate to change the environment (such as temperature, humidity, lighting, noise, dust, germs and airflow) in a certain space according to the demand side requirement by the time and zoning.
If we can satisfy the demand to be more detailed and more comfortable, we can save energy naturally.

Environmental Conservation　
Recovery of wasted energy and the use of natural energy do not only save energy, but also contribute to environmental conservation by not disturbing the ecological balance.

Cutting-edge Technology
High-efficiency equipments that meet demand side requirements have been developed, and using them will help save energy.

The Importance of Maintenance Management
Appropriate daily maintenance is necessary for the equipments to operate and function adequately. Without appropriate inspection and maintenance, excess energy is burned off because of heat release, over heat, vibration, noise and leaks in the equipment system. Inadequate cleaning can cause energy inefficiency in lighting, air conditioning and ventilation equipments.

The Importance of Overall System Efficiency
For all the buildings to function and perform well, overall system efficiency described above is probably the most improtant thing to consider.