Research and Study on All-Electric Homes in Northern Regions Using Heat Pumps

Considering that the reduction of carbon-dioxide emissions is an urgent issue among the measures against global warming while household energy consumption is increasing, we need to implement further energy saving in housing equipment.

Therefore it is important to promote heat pumps which can effectively generate hot and cold energy, taking advantage of the safe, secure and clean characteristics of electricity. We have researched and more studies on all-electric homes in the northern regions using heat pumps in both simulation and field surveys. This is because the establishment of an introduction methods for heat pump systems which are suited for climates and housing in Hokkaido is considered to contribute to the reduction of energy consumption.

In Hokkaido, central hot water heating systems with panel radiators are widely used. Therefore, when heat pumps are installed, hot-water heat source equipment is adopted. On the other hand, heating equipment for cold regions including hot-air heat pump heating equipment (room-air conditioners) is also increasingly developed.

In a hot-water heating system, it is important to design it as a system since it can change its efficiency according to the capacity of radiators. But, there is no established method to solve the problem. Thus, we aim at "modeling a hot-water piping system" based on field surveys in housing and "developing selection tools for radiators and piping systems suited for housing" using a characteristic formula for radiators.

We also closely survey the temperature distribution in actual housing since we do not have enough data on indoor thermal environments in the house which uses a hot-air heating system. We aim at establishing a proper design method through simulation for insulation levels and the location of the equipment in housing.

In hot-water heating systems, we have collected and compiled the basic data for an optimal design. In hot-air heating systems, we installed air conditioners in the field and made surveys (see Fig.1). In order to find the difference between this system and panel heating (see Fig.2) as the thermal environment, we have collected data on temperature and wind velocity distribution, and on the operation of the equipment. Comparing this data, we could not find big difference between hot-air heating and panel heating, and hot-air heating utilizing heat pump room-air conditioner shows a similar temperature distribution to the one of panel heating in living area.