Indoor climate - Shitsunaikikou (English spelling)

Japanese: 室内気候 - しつないきこう（英語表記）indoor climate

This refers to the overall climatic state of the indoor air caused by thermal environmental factors such as temperature, humidity, airflow speed, and thermal radiation inside a building. It is also called indoor climate or indoor thermal environment. Because the interior of a room is separated from the outside world by exterior walls, the indoor climate is not directly affected by the outside temperature and humidity, solar radiation, external wind speed, etc., but is somewhat mitigated. The degree of mitigation depends on the building structure, the material of the surrounding walls, the thermal properties of indoor objects, the building's orientation, the amount of ventilation, the amount of heat supplied to the room, etc.

Indoor air temperature is the most important factor in expressing indoor climate, and is also simply called room temperature. Room temperature fluctuates over time, mainly depending on the outdoor temperature, solar radiation, and the amount of heat supplied to the room. When heat is supplied to the room, some of the heat increases the temperature of the indoor air and surrounding walls, while the rest passes through the walls or is lost to the outside through ventilation. The amount of heat that flows into or out of the room in one hour when the temperature difference between the indoor and outdoor temperatures is 1°C is called the room's heat loss coefficient W, and the amount of heat stored in the surrounding walls and indoor air when the room temperature is raised by 1°C is called the room's heat capacity Q. The ratio of W to Q is called the room temperature fluctuation rate, which indicates how quickly the room temperature changes. If any one of the outdoor temperature, solar radiation, or heat supply increases, the room temperature will also rise, but the rate of increase is greater in rooms with a higher room temperature fluctuation rate, so the smaller the room's heat capacity and the higher the room's heat loss coefficient, the greater the room temperature will fluctuate. Buildings made of brick, concrete, and earthen storehouses have a small rate of fluctuation in room temperature and are less affected by fluctuations in heating and outside temperature, but buildings made of wood and shacks have a large rate of fluctuation in room temperature and experience drastic changes in room temperature.

Approximately 20% or less of the energy produced by the human body through the intake of food and oxygen is used for various human movements, and the remainder is dissipated as heat from the body in the form of conduction, convection, radiation, and water evaporation. When the amount of heat lost is greater than the amount of heat produced, the human body feels cold, and in order to maintain body temperature, the thermoregulatory function works to increase heat production and maintain heat balance. The range of thermal environmental conditions that are neither hot nor cold and in which the human body's heat balance is balanced with minimal physiological effort is called the comfort zone, and when the reading is expressed in temperature, it is called the optimal temperature.

The sensation of hotness or cold, which is perceived due to differences in the heat balance of the human body, is not influenced by each element of the thermal environment acting alone, but by various combinations of elements acting comprehensively. Therefore, it is possible to evaluate the thermal environment by evaluating all of these elements individually, but since this evaluation method is complicated and unintuitive, research has been conducted since around 1910 on evaluation methods that express the thermal environment with a single comprehensive index that combines as many elements as possible. The main indexes are operative temperature, humid operative temperature, effective temperature, modified effective temperature, and new effective temperature.

[Masayuki Mizuhata]

OT, HOT

The operative temperature is an index that expresses the combined effect of air temperature and radiation on the human body's sensation. It is also called effective temperature and is abbreviated as OT (operative temperature). It is defined as the temperature of a room with a certain air temperature and the average radiation temperature of the surrounding walls, which is equal to the air temperature and the average radiation temperature that receive the same amount of heat as the human body receives. In a normal room, the average radiation temperature is approximately equal to the average surface temperature of the surrounding walls. The humid operative temperature is an index of sensation that takes into account the effect of humidity in addition to the operative temperature. It is abbreviated as HOT (humid operative temperature). It is the room temperature of a room with a certain air temperature, the average radiation temperature of the surrounding walls, and the humidity of 100%, which is equal to the air temperature and the average radiation temperature that receive the same amount of heat as the human body receives, and is said to be close to the effective temperature when wearing a jacket.

[Masayuki Mizuhata]

Effective Temperature (ET), Corrected Effective Temperature (CET)

Effective temperature is a single index that expresses the combined effect of three elements, air temperature, humidity, and wind speed, on the body sensation, and was proposed by FC Houghton and CP Yaglou in 1923. It is also called the sensory temperature and is abbreviated as ET (effective temperature). ET is the air temperature in a windless room with 100% humidity that has the same sensation as any combination of the three elements, and was determined based on a subjective survey of subjects. A chart that calculates the effective temperature from any combination of the three physical elements under certain clothing and work conditions is called an effective temperature chart. Yaglou himself pointed out in 1947 that the effect of humidity on the body sensation in ET is overestimated in low temperature ranges and underestimated in high temperature ranges. In addition, since the effect of thermal radiation is not considered in ET, taking this into consideration, the globe temperature is used instead of the dry-bulb temperature, and the equivalent wet-bulb temperature (the wet-bulb temperature shown when the dry-bulb temperature changes to the globe temperature while the absolute humidity remains constant) is used instead of the wet-bulb temperature, and the effective temperature is obtained from the same effective temperature chart. This is called the corrected effective temperature, abbreviated as CET. ET or CET was widely used until around 1970 as an index that accurately represents the human sensation.

[Masayuki Mizuhata]

New effective temperature (ET ^* )

The new effective temperature was proposed by AP Gagge et al. in 1971 based on the aforementioned criticisms and research on ET, and is abbreviated as ET ^* (new effective temperature). It is defined as the temperature in a windless room with a humidity of 50% where the average radiant temperature is equal to the air temperature, and applies to a lightly clothed sitting human body. ^ET* is the most rational index of body sensation derived from an analysis of the heat balance of the human body, and is fundamentally different from ET. A chart for calculating ET ^* for a given temperature and humidity environment is called the new effective temperature chart. A temperature of 23-25°C and a humidity of 20-60% are recommended as comfort zones.

In addition to the above thermal environment indices, the Kata thermometer was invented by L. Hill in 1916 to measure the combined effect of air temperature and wind speed on thermal comfort, and it was proposed that the Kata cooling power measured with this instrument be used as a thermal environment index, but this index has a limited range of compatibility with thermal comfort and is not used much today. Because the Kata cooling power is expressed as a function of wind speed, the Kata thermometer is used more as a simple anemometer.

[Masayuki Mizuhata]

[Reference] | Air conditioning | Artificial climate | Panel heating | Damp-proof design

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

建物内の温度、湿度、気流速、熱放射などの熱環境要素によって生じる室内空気の総合的気候状態をいう。屋内気候、室内熱環境ともいう。室内は外壁によって外界と隔てられているから、室内気候は外気温湿度、日射、外部風速などの影響を直接受けるのではなく、いくぶん緩和される。その程度は、建物の構造、周壁の材料、室内物体などの熱的性質、建物の方位、換気量、室内供給熱量などに関係する。

　室内気温は室内気候を表すもっとも重要な要素であり、単に室温ともいう。室温はおもに外気温、日射量、室内供給熱量の大きさによって時間的に変動する。熱が室内に供給されると、その熱の一部は室内空気と周壁の温度を高め、その残りは壁を貫流し、あるいは換気によって室外に流失する。室内外の気温差1℃のときに1時間に室内に流入もしくは室内から流出する熱量を室の熱損失係数Wといい、室温を1℃高めたときに周壁および室内空気に蓄えられる熱量を室の熱容量Qという。また、Qに対するWの比を室温変動率といい、室温変化の速さの程度を表す。外気温、日射量、供給熱量のいずれか一つの量が大になれば室温も上昇するが、その上昇速度は室温変動率が大きい室ほど大きいので、室の熱容量が小さいほど、また室の熱損失係数が大きいほど室温は大きく変動する。れんが造、コンクリート造、土蔵などは室温変動率が小さく、暖房や外気温などの変動の影響を受けにくいが、木造、バラックなどの室温変動率の大きな建物は室温の変化が激しい。

　食物と酸素の摂取によって生み出される人体のエネルギーの約2割以下は人間の種々の動作に費やされ、残りは熱として伝導、対流、放射および水分蒸発の形態をとって体外に放散される。放熱量が産熱量よりも大きいときには、人体は寒いと感じ、体温を保つために、体温調節機能の働きによって産熱量を増加させて熱収支の均衡を保つ。最小の生理的努力によって人体の熱収支が平衡するような、暑くも寒くもない熱環境状態の範囲を快適帯といい、その示度を温度で表す場合には、これを至適温度という。

　人体の熱収支の差によって知覚される暑さ・寒さの体感に対して、熱環境の各要素が単独に作用するのではなく、各要素の種々の組合せによって総合的に作用している。したがって、これらのすべての要素を個々に評価することによって熱環境を評価することも可能であるが、この評価法は複雑であり、直観性がないので、熱環境を、できるだけ多くの要素が組み合わされた総合的な単一指標で表す評価法の研究が1910年ごろから行われてきた。その指標のおもなものに作用温度、湿り作用温度、有効温度、修正有効温度、新有効温度がある。

［水畑雅行］

作用温度（OT）、湿り作用温度（HOT）

作用温度は、体感に対する気温と放射の総合効果を表す指標で、効果温度ともいわれ、OT（operative temperature）と略記される。これは、ある気温、周壁の平均放射温度の室において、人体が受ける熱量と等しい受熱をする気温および平均放射温度とを等しくした室の気温と定義されている。平均放射温度は通常の室では、その室の周壁表面温の平均値にほぼ等しい。湿り作用温度は、作用温度に湿度の影響を加味した体感指標で、HOT（humid operative temperature）と略記される。これは、ある気温、周壁平均放射温度、湿度の室において、人体が受ける熱量と等しい受熱をする湿度100％における気温および平均放射温度とを等しくした室の気温であり、上衣を着た場合の有効温度によくあうといわれている。

［水畑雅行］

有効温度（ET）、修正有効温度（CET）

有効温度は、気温、湿度、風速の3要素の体感に及ぼす総合効果を表す単一指標で、1923年にホートンF. C. HoughtonとヤグローC. P. Yaglouによって提案された。これは感覚温度ともいわれ、ET（effective temperature）と略記される。ETは3要素の任意の組合せによる体感と等しい体感をもった湿度100％、無風室の気温で、多数の被験者の主観的な体感申告調査に基づいて決められた。一定の着衣および作業状態における任意の3要素の物理量の組合せから有効温度を求める図表を有効温度図という。ETは低温域では体感に及ぼす湿度の影響が過大視され、高温域では過小評価されていることが、1947年にヤグロー自身によって指摘された。また、ETには熱放射の影響が評価されていないので、これを考慮して、グローブ温度を乾球温度のかわりに用い、相当湿球温度（絶対湿度が不変で、乾球温度がグローブ温度に変化したときに示す湿球温度）を湿球温度のかわりに用いて、同じ有効温度図から有効温度を求める示度を修正有効温度といい、CET（corrected effective temperature）と略記される。ETまたはCETは体感をよく表す指標として1970年ごろまで広く用いられてきた。

［水畑雅行］

新有効温度（ET^*）

新有効温度は、前述のETに対する批判や研究に基づいて1971年ガッゲA. P. Gaggeらによって提案され、ET^*（new effective temperature）と略記される。これは、平均放射温度が気温に等しい湿度50％、無風の室の気温と定義され、軽装座位の人体に適用される。ET^*は、人体の熱収支の解析に基づいて導かれたもっとも合理的な体感指標であり、ETとは本質的に異なる。ある温湿度の環境のET^*を求める図表を新有効温度図という。快適帯として気温23～25℃、湿度20～60％が推奨されている。

　以上のような熱環境指標のほかに、体感に対する気温と風速の総合効果を測定するために、カタ温度計がヒルL. Hillによって1916年に考案され、これによって測定されるカタ冷却力を熱環境指標とする提案がなされたが、この指標は体感との適合範囲が限られており、今日ではあまり用いられない。カタ冷却力は風速の関数で表されるので、カタ温度計はむしろ簡易な微風速計として用いられる。

［水畑雅行］

[参照項目] | 空気調和 | 人工気候 | パネル・ヒーティング | 防湿設計

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例

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