question: why is a room heated to 65 quite comfortable, but a room cooled to 65 is freezing!?!?
comment: Temperature contrast and adaptation difference. When the room is heating, your body adapted to the cooler temperature, thus it relaxes and your blood vessels slightly expand (they were contracted to lose less heat). When the room is cooling that means your body adapted to conduct more temperature (expanded blood vessels to prevent overheating) and cooling brings some shock, thus your vessels have to contract due to the potential risk of freezing. Same goes with contrast showers — you alternating hot and cold water, thus providing a slight thermal shock to the body. It may be good for your blood vessels tonus, but some people may suffer panic attacks because of them.
passages: Colloquially, room temperature is the range of air temperatures that most people prefer for indoor settings, which feel comfortable when wearing typical indoor clothing. Human comfort can extend beyond this range depending on humidity, air circulation and other factors. In certain fields, like science and engineering, and within a particular context, room temperature can mean different agreed-on ranges. In contrast, "ambient temperature" is the actual temperature of the air (or other medium and surroundings) in any particular place, as measured by a thermometer. It may be very different from usual room temperature, for example an unheated room in winter.
   Whenever the studies referenced tried to discuss the thermal conditions for different groups of occupants in one room, the studies ended up simply presenting comparisons of thermal comfort satisfaction based on the subjective studies. No study tried to reconcile the different thermal comfort requirements of different types of occupants who compulsorily must stay in one room. Therefore, it looks to be necessary to investigate the different thermal conditions required by different groups of occupants in hospitals to reconcile their different requirements in this concept. To reconcile the differences in the required thermal comfort conditions it is recommended to test the possibility of using different ranges of local radiant temperature in one room via a suitable mechanical system.
   Section::::Comfort levels.
  
  "The American Heritage Dictionary of the English Language" identifies room temperature as around , while the "Oxford English Dictionary" states that it is "conventionally taken as about ".
  
  Owing to variations in humidity and likely clothing, recommendations for summer and winter may vary; a suggested typical range for summer is , with that for winter being , although by other considerations the maximum should be below  – and to avoid sick building syndrome, below .
  
  Some studies have suggested that thermal comfort preferences of men and women may differ significantly, with women on average preferring higher ambient temperatures.
   Since there are large variations from person to person in terms of physiological and psychological satisfaction, it is hard to find an optimal temperature for everyone in a given space. Laboratory and field data have been collected to define conditions that will be found comfortable for a specified percentage of occupants.
   The “radiation effect” results from radiation heat exchange between human bodies and surrounding surfaces, such as walls and ceilings. It may lead to phenomena such as houses feeling cooler in the winter and warmer in the summer at the same temperature. For example, in a room in which air temperature is maintained at 22° Celsius at all times, but in which the inner surfaces of the house is estimated to be an average temperature of 10° Celsius in the winter or 25° Celsius in the summer, heat transfer from the surfaces to the individual will occur, resulting in a difference in the perceived temperature.
   We can observe and compare the rate of radiation heat transfer between a person and the surrounding surfaces if we first make a few simplifying assumptions: 
  
  BULLET::::- The heat exchange in the environment is in a “steady state”, meaning that there is a constant flow of heat either into or out of the house.
  
  BULLET::::- The person is completely surrounded by the interior surfaces of the room.
  
  BULLET::::- Heat transfer by convection is not considered.
  
  BULLET::::- The walls, ceiling, and floor are all at the same temperature.
   The World Health Organization's standard for comfortable warmth is for normal, healthy adults who are appropriately dressed. For those with respiratory problems or allergies, they recommend no less than , and for the sick, disabled, very old or very young, a minimum of .
  
  Section::::Definitions in science and industry.
   Section::::Concepts.:Thermal comfort.:Thermal neutrality.
  
  Thermal Neutrality (Thermal Neutral Zone) is the temperature range where it is neither comfortable or uncomfortable. The human body's metabolism is burning calories at the same rate as the temperature around. This would be around 24 °C (room temperature), and people have no opinion about the temperature. Thermal Neutrality is often also used in animal raising.For example, Farmers maintain the neutral temperature for cattle to prevent Cold Stress.
  
  Section::::Concepts.:Thermal comfort.:Everyday uses.
  
  BULLET::::- Floor Surface Temperature - too hot or too cold floors cause discomfort, people wear light shoes or have heated floors.
   Temperature ranges are defined as "room temperature" for certain products and processes in industry, science, and consumer goods. For instance, for the shipping and storage of pharmaceuticals, the United States Pharmacopeia-National Formulary (USP-NF) defines "controlled room temperature" as between , with excursions between allowed, provided the mean kinetic temperature does not exceed . The European Pharmacopoeia defines it as being simply , and the Japanese Pharmacopeia defines "ordinary temperature" as , with room temperature being . Merriam-Webster gives as a medical definition a range of as being suitable for human occupancy, and at which laboratory experiments are usually performed.
   Thermal comfort as a "condition of mind" is "defined" in psychological terms. Among the factors that affect the condition of mind (in the laboratory) are a sense of control over the temperature, knowledge of the temperature and the appearance of the (test) environment. A thermal test chamber that appeared residential "felt" warmer than one which looked like the inside of a refrigerator.
  
  Section::::Models.:Adaptive comfort model.:Physiological Adaptation.
   It differs from other forms of electromagnetic radiation such as x-rays, gamma rays, microwaves, radio waves, and television rays that are not related to temperature. Scientists have found that all bodies at a temperature above absolute zero emit thermal radiation. People are constantly radiating their body heat, but at different rates. From these values, the rate of heat loss from a person is almost four times as large in the winter than in the summer, which explains the “chill” we feel in the winter even if the thermostat setting is kept the same.
   BULLET::::- Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls.
  
  BULLET::::- Homogeneous interior temperature: it is impossible to have single rooms (e.g. the sleeping rooms) at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.
   Room Temperature (novel)
  
  Room Temperature is Nicholson Baker's second book, and continues the genre established in his first novel "The Mezzanine", though this time the action spans a few minutes at the narrator's home (in Quincy, Massachusetts).
   Section::::Models.:PMV/PPD method.:Local thermal discomfort.:Radiant temperature asymmetry.
  
  Large differences in the thermal radiation of the surfaces surrounding a person may cause local discomfort or reduce acceptance of the thermal conditions. ASHRAE Standard 55 sets limits on the allowable temperature differences between various surfaces. Because people are more sensitive to some asymmetries than others, for example that of a warm ceiling versus that of hot and cold vertical surfaces, the limits depend on which surfaces are involved. The ceiling is not allowed to be more than + warmer, whereas a wall may be up to + warmer than the other surfaces.
   As Newton's law of cooling states, the rate of cooling of an object - whether by conduction, convection, or radiation - is approximately proportional to the temperature difference Δ"T". Frozen food will warm up faster in a warm room than in a cold room. Note that the rate of cooling experienced on a cold day can be increased by the added convection effect of the wind. This is referred to as wind chill. For example, a wind chill of -20 °C means that heat is being lost at the same rate as if the temperature were -20 °C without wind.
   When the addition was added in 1964, its more modern design did not go well with the older section, and in the 1980s, a major renovation of the building took place, and this problem was corrected.
   The rate of cooling of an object depends on how much hotter the object is than its surroundings. The temperature change per minute of a hot apple pie will be more if the pie is put in a cold freezer than if it is placed on the kitchen table. When the pie cools in the freezer, the temperature difference between it and its surroundings is greater. On a cold day, a warm home will leak heat to the outside at a greater rate when there is a large difference between the inside and outside temperatures. Keeping the inside of a home at high temperature on a cold day is thus more costly than keeping it at a lower temperature. If the temperature difference is kept small, the rate of cooling will be correspondingly low.
   In building science studies, thermal comfort has been related to productivity and health. Office workers who are satisfied with their thermal environment are more productive. The combination of high temperature and high relative humidity reduces thermal comfort and indoor air quality.
   This model applies especially to occupant-controlled, natural-conditioned spaces, where the outdoor climate can actually affect the indoor conditions and so the comfort zone. In fact, studies by de Dear and Brager showed that occupants in naturally ventilated buildings were tolerant of a wider range of temperatures. This is due to both behavioral and physiological adjustments, since there are different types of adaptive processes. ASHRAE Standard 55-2010 states that differences in recent thermal experiences, changes in clothing, availability of control options, and shifts in occupant expectations can change people's thermal responses.
   Section::::Thermal comfort.
  
  The operative temperature is an indicator of thermal comfort which takes into account the effects of both convection and radiation. Operative temperature is defined as a uniform temperature of a radiantly black enclosure in which an occupant would exchange the same amount of heat by radiation plus convection as in the actual nonuniform environment.
  
  With radiant systems, thermal comfort is achieved at warmer interior temp than all-air systems for cooling scenario, and at lower temperature than all-air systems for heating scenario.
   BULLET::::5. "Cold Comfort" - After a contractor failed to properly insulate a new addition, a bedroom became cold and unlivable in winter. With a court case pending, Mike Holmes tears open the ceiling, insulates properly and finds numerous other problems that need fixing.
  
  BULLET::::6. "Flimsy Floor" - When a brand new kitchen addition floor buckles during a party, a "quick-fix" by the contractor fails to solve the problem. Mike Holmes secures the floor's joists, adds braces and reminds us that structure is just as important as design.
   This research is applied to create Building Energy Simulation (BES) programs for residential buildings. Residential buildings in particular can vary much more in thermal comfort than public and commercial buildings. This is due to their smaller size, the variations in clothing worn, and different uses of each room. The main rooms of concern are bathrooms and bedrooms. Bathrooms need to be at a temperature comfortable for a human with or without clothing. Bedrooms are of importance because they need to accommodate different levels of clothing and also different metabolic rates of people asleep or awake. Discomfort hours is a common metric used to evaluate the thermal performance of a space.
   Section::::Production.:Picture and sound.
   Section::::Methods to evaluate thermal comfort.:Local thermal discomfort.
  
  Radiant temperature asymmetry between ceiling and floor, and air and walls must be limited to reduce discomfort. To reduce draft risk at temperatures below , air speed due to the HVAC system must be or below. The vertical air temperature difference between ankle and head is limited to for seated occupants and for standing occupants. If occupants' feet will be in contact with the floor, the temperature must be .
  
  Section::::Methods to evaluate thermal comfort.:Temperature variations with time.
   Section::::Features.
  
  Section::::Features.:Thermal comfort quality.
  
  As defined by ANSI/ASHRAE Standard 55 – Thermal Environmental Conditions for Human Occupancy, thermal comfort is, "that condition of mind which expresses satisfaction with the thermal environment and is assessed by subjective evaluation." Relating specifically to underfloor heating, thermal comfort is influenced by floor surface temperature and associated elements such as radiant asymmetry, mean radiant temperature and operative temperature. Research by Nevins, Rohles, Gagge, P. Ole Fanger et al. show that humans at rest with clothing typical of light office and home wear, exchange over 50% of their sensible heat via radiation.
  