Investigation of Indoor Thermal Environment, Air Quality, and Energy Consumption in New Detached Houses of Wood-Frame Construction in a Small City in Japan
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EnvironmenJ International, Vol. 16, pp. 37 - 52, 1990 0160-4120/90 $3.00 +.00 Printed in the U.S.A. All rights reserved. Copyright @ 1990 Pergamon Press pie INVESTIGATION OF INDOOR THERMAL ENVIRONMENT, AIR QUALITY, AND ENERGY CONSUMPTION IN NEW DETACHED HOUSES OF WOOD-FRAME CONSTRUCTION IN A SMALL CITY IN JAPAN Hiroshi Yoshino, Hiroshi Matsumoto, and Kazushi Makita Tohoku University, Sendai, Japan Fusao Hasegawa Tohoku Institute of Technology, Sendai, Japan Yasuo Utsumi Miyagi National College of Technology, Natori, Japan Shin-ichi Akabayashi Tokyo University, Tokyo, Japan EI 87-151 (Receitied 9 Not1ember 1987; Accepted 7 February 1989) The authors investigated indoor thermal environment, airtightness, indoor air quality, and energy consumption in thirteen new houses of wood-frame construction in a local city of Japan in the winter of 1985. All houses had thermally-insulated walls, ceilings, and floors, except for one house which had a concrete floor without insulation under the floor. Eight houses had concrete floors on the first level of the structure. Seven houses out of eight had hot-water pipes embedded in the concrete for floor heating and thermal insulation under the floor on the grade. Three houses out of seven also had fan coil units in the bedrooms on the second floor. The six other houses without floor heating had oil or gas local space heaters. The authors found differences in temperature profiles between the houses with floor heating and those with space heaters. The effective leakage area per floor area obtained by the fan pressurization method was distributed 2 2 from 3.8 to 16 cm /m • The concentration measurements of C02 and N02 in the living rooms showed that the two houses with unvented oil space heaters were more polluted than the other houses. The total annual amount of energy consumption was distributed from 46 to 100 OJ. INTRODUCTION cases, that is, the depth of fiberglass insulation in the ceiling, walls, and floor is 20 cm, 15 cm, and 10 cm, In Hokkaido, the northern-most island of the Jap respectively. anese Archipelago, the newly constructed residential buildings are well insulated and well heated due to On the other hand, the Japanese national govern the severe climate in the winter and to the significant ment passed legislation concerning building insula concern for improvement of the indoor thermal envi tion standards for the first time after the oil crisis in ronment since the end of the World War II. The 1973. This law prescribed a recommendation for the Hokkaido local government originally passed legis insulation performance of a housing envelope in each lation concerning the insulation of houses. This law region of Japan. As a result, the mean ratio of newly has been revised several times. Nowadays, newly constructed houses with a partially or totally insu constructed houses have heavy insulation in many lated envelope in 1985 was 88 % in all of Japan 37 38 H. Yoshino et al. according to the survey of the Glass Wool (Fiber two types; one was an unvented heater and the other glass) Association of Japan. Also, in Sendai, a local was a vented heater. An unvented heater takes in city in the Tohoku region, newly constructed de room air for combustion and expels the exhaust into tached houses have become more and more airtight the room. A vented heater takes in outside air for and highly insulated. In such houses, it is expected combustion and expels the exhaust outdoors. House that the quality of the indoor thermal environment no. 2 had an unvented oil space heater, which sup will be better than that of existing houses. But there plied hot air by a fan, for the living/dining room. is the possibility of indoor air pollution, because House no. 4 had a vented oil heater for the living unvented oil or gas space heaters are still popular in room as well as an unvented portable oil heater for many homes. the dining room. The other houses had vented oil The authors have investigated indoor temperature, heaters for the living room or the living/dining room. airtightness, indoor air quality, and energy consump The main bedrooms measured had no space heater. tion in 13 units of new, detached houses in Sendai. The houses constructed by contractors "B" and "C" There are many existing reports which reveal indoor had concrete floors, including hot water pipes for temperature or indoor.air quality in Japan. For exam floor heating and thermal insulation between the floor ple, Hasegawa and Yoshino (1987) showed the re and the ground. The exception was house no. 6, which sults of indoor temperature measurements of 139 had a concrete floor without floor heating, but had a houses in the Tohoku region and compared them with vented oil heater for the living and dining rooms. The other measurement studies. And Nakai et al. (1987) three houses out of seven with floor heating also had reported the results of N02 concentration measure- . fan coil units in the bedrooms of the, second floor. In men ts in all-electric houses and houses using ·gas to · six houses out of thirteen with a space heater or floor prepare meals; However, there are no reports which heating, an electric heater "Kotatsu" is also used in investigate many factors relating to indoor climate the living room. A "Kotatsu" is a Japanese style and energy consumption in houses. electric heater which is mounted under a low table Sendai is the main city of the Tohoku region, which covered with a quilt. People sitting on the floor heat is in the northern portion of Honshu Island, and is their legs under the low table. located near the coast of the Pacific Ocean. The The investigated structures without floor heating latitude of Sendai is 38°16'. The mean outdoor tem were typical among the newly-built houses in Sendai, perature in January is 0.9°C. but the houses with floor heating are not so popular and are built by only two or three contractors. The DESCRIPTION OF HOUSES MEASURED AND measurements were made during January and Febru MEASUREMENT PERIOD ary of 1985. Table 1 des.cribes the houses measured. All houses INDOOR THERMAL ENVIRONMENT were built bi the wood-frame construction method. The floor area of the houses measures from 105 to Method of measurement 183 m2, which was nearly equal to or larger than the average of detached wooden houses throughout Japan Temperatures at six points in each house were [105 m2 in 1983, as given by the Bureau of Statistics, measured continuously for seven to ten days by re Office of the Prime Minister, (1984)]. The occupants sistance thermometers. The number of days for mea are the middle classes. Figure 1 illustrates the floor surement was different between the houses because of plans of the first floors of the houses in this study. the need to accommodate the occupants. The points These houses were constructed between 1981 and measured, which are shown in Fig. 1,, were in the living 1984. All of the structures have thermally insulated room (5 cm and 1.1 m above the floor level), the main walls, ceilings, and floors, except for house no. 6 bedroom, the entrance hall, outside the house, etc. which has a concrete floor without insulation under Radiant temperature was measured by using a globe it. The insulation material used was fiberglass. The thermometer in the living room at a point 1.1 m above depth of insulation in house no. 7, for example, which the floor level. is the most heavily insulated, is 15 cm for the walls and ceiling, and 5 cm for the floor. The windows of Outdoor temperature during the measurement period all houses had double glazing or double sashes. The average outdoor temperature was about -0.6°C The houses constructed by contractor "A" had oil for the first half of the measurement period (Jan. 25 or gas space heaters for heating at least the living to Feb. 3) and about 2.3°C for the latter half of that room. The oil or gas space heaters were divided into period (Feb. 5 to 12):· Indoor air quality in Japan 39 Table 1. Description of measured houses. House Date of Floor Depth of insulation Window Heating in living room num- completion area (cm)t Equipment Hours* Months ber (m2) in a day in a year Wall EIQQI: Qeilio.g it";~ " 1 Jan.1983 109 5 5 7.5 D.S. Vented oil heater 9.8 ' 2 Jan.,1983 105 5 5 7.5 D.S. Unvented oil heater 8.9 4.6 & "Kotatsu" 3 Jan.1983 109 5 5 7.5 .. D.S. Vented . ~as heater 6.5 4.6 4 Mar.1983 110 5 5 7.5 D.S. Unvented_&··vented 8.9 4.3 oil heaters .. 5 Dec.1984 109F 10· 2.5 10 D.S. Floor heating & 2.0 morning : !• "Kotatsu" 1.5 evening 6 Sept.1984 142F 10 10 D.S. Vented oil heater & 9.9 4.3 "Kotatsu" 7 ', : Sept.1984 183F 15 5 15 D.S. Floor heating 2.0 morning 2.0 8 Jap. .1982 110. 5 5 7.5 D.G. Vented oil heater & 10.2 4.3 . "Kotatsu" :. 9 bci.1984 152F 5c•. 5 10 D.S.' Floor heating 2,0 morning } ' - 2~0 evening 10 Mar.1983 147F · ·5 5 10 D.G. Floor heating & ,. 1.0 morning 6.6 "Kotatsu" 2.5 evehing n Aug.1983. 163F 5 5 10 D.S. Floor heating 2.5 morning 4_0 3.0 evening , I 12 June1981 120F 5 5 10 D.G.