question: When it’s cold outside, why is our natural instinct to make it warm inside the house instead of just room temperature?
comment: Because most homes don't have energy efficient doors and windows, so the cold air seeps into the house making it feel colder ...so we heat to compensate.
passages: Section::::Models.:Adaptive comfort model.:Behavioral Adaptation.
  
  In naturally ventilated buildings, occupants take numerous actions to keep themselves comfortable when the indoor conditions drift towards discomfort. Operating windows and fans, adjusting blinds/shades, changing clothing, and consuming food and drinks are some of the common adaptive strategies. Among these, adjusting windows is the most common. Those occupants who take these sorts of actions tend to feel cooler at warmer temperatures than those who do not.
   Passive design improves thermal comfort in a building, thus reducing demand for heating or cooling. In many developing countries, however, most occupants do not currently heat or cool, due to economic constraints, as well as climate conditions which border lines comfort conditions such as cold winter nights in Johannesburg (South Africa) or warm summer days in San Jose, Costa Rica. At the same time, as incomes rise, there is a strong tendency to introduce cooling and heating systems. If we recognize and reward passive design features that improve thermal comfort today, we diminish the risk of having to install HVAC systems in the future, or we at least ensure that such systems will be smaller and less frequently used. Or in case the heating or cooling system is not installed due to high cost, at least people should not suffer from discomfort indoors. To provide an example, in San Jose, Costa Rica, if a house were being designed with high level of glazing and small opening sizes, the internal temperature would easily rise above and natural ventilation would not be enough to remove the internal heat gains and solar gains. This is why Virtual Energy for Comfort is important.
   Later, human beings’ long life span and development of agriculture determined that they needed a fixed place of residence, earth-sheltered houses, stone houses, and cave dwellings began to emerge. The high density of these materials can cause a time lag effect in thermal transfer, which can make the inside temperature change slowly. This effect keep inside of the buildings warm in winter and cool in summer, also because of the materials like earth or stone is easy to get, this design is really popular in many places like Russia, Iceland, Greenland.
   Use of passive natural ventilation is an integral component of passive house design where ambient temperature is conducive — either by singular or cross ventilation, by a simple opening or enhanced by the stack effect from smaller ingress with larger egress windows and/or clerestory-operable skylight.
   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.
   Section::::Controls of variables.
  
  Section::::Controls of variables.:Core temperature.
  
  Mammals regulate their core temperature using input from thermoreceptors in the hypothalamus, brain, spinal cord, internal organs, and great veins. Apart from the internal regulation of temperature, a process called allostasis can come into play that adjusts behaviour to adapt to the challenge of very hot or cold extremes (and to other challenges). These adjustments may include seeking shade and reducing activity, or seeking warmer conditions and increasing activity, or huddling.
   One type of coating (low-e coatings) reduces the emission of radiant infrared energy, thus tending to keep heat on the side of the glass where it originated, while letting visible light pass. This results in glazing with better control of energy - heat originating from indoors in winter remains inside (the warm side), while heat during summer does not emit from the exterior, keeping it cooler inside.
   It has been suggested that energy intake also increases during conditions of extreme or prolonged cold temperatures. Relatedly, researchers have posited that reduced variability of ambient temperature indoors could be a mechanism driving obesity, as the percentage of US homes with air conditioning increased from 23 to 47 percent in recent decades. In addition, several human and animal studies have shown that temperatures above the thermoneutral zone significantly reduce food intake. However, overall there are few studies indicating altered energy intake in response to extreme ambient temperatures and the evidence is primarily anecdotal.
  
  Section::::Environmental influences.:Ambient characteristics.:Lighting.
   Human comfort depends on five criteria, two of which concern one’s clothing and metabolism, and three others which focus on air temperature, air humidity and airflow speed. The faster the airflow is on someone the cooler he feels. Moreover, natural ventilation brings sound fresh air into the building when well-designed. Thus, natural ventilation tends to increase comfort as well as health in tropical climates and aims to suppress air conditioning.
   In Central Europe and most of the United States, for unobstructed south-facing Passivhaus windows, the heat gains from the sun are, on average, greater than the heat losses, even in mid-winter.
  
  Section::::Design and construction.:Airtightness.
   In order to reduce these factors the heating radiators are always placed under window sills. As far as people can feel cold and heat, the actual temperature of environment is not the only factor which defines the total level of comfort. In reality, the heat radiation of surrounding surfaces has a greater influence than air temperature. If the window surface is cold then to maintain the comfort atmosphere it is necessary to increase the heating temperature, but it will also increase energy consumption. 
   Section::::Physiological adaptations.:Acclimatization.
  
  When humans are exposed to certain climates for extended periods of time, physiological changes occur to help the individual adapt to hot or cold climates. This helps the body conserve energy.
  
  Section::::Physiological adaptations.:Acclimatization.:Cold.
   To that end, clerestories are used in conjunction with stone, brick, concrete, and other high-mass walls and floors, properly positioned to store solar heat gains during the hotter parts of the day – allowing the walls and the floor to act as a heat bank during the cooler parts of the day.
  
  Clerestories – in passive solar strategies – should be properly located (typically in the sunny side of the building) and protected from the summer’s sun by rooflines, overhangs, recessed thick walls, or other architectural elements, in order to prevent overheating during the cooling season.
  
  Section::::Transportation.
   In many post-occupancy comfort studies overheating is a frequently reported problem not only during the summer months but also during the transitions periods, also in temperate climates.
  
  Section::::Potentials and limitations.
   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 pressure can be either positive or negative with respect to outside the room. Positive pressure occurs when there is more air being supplied than exhausted, and is common to reduce the infiltration of outside contaminants.
  
  Section::::Ventilation.:Natural ventilation.:Airborne diseases.
  
  Natural ventilation is a key factor in reducing the spread of airborne illnesses such as tuberculosis, the common cold, influenza and meningitis. Opening doors, windows, and using ceiling fans are all ways to maximize natural ventilation and reduce the risk of airborne contagion. Natural ventilation requires little maintenance and is inexpensive.
  
  Section::::Air conditioning.
   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.
   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.
   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.
   Air changes are often cited as a means of preventing condensation in houses with forced ventilation systems often rated from 3 - 5 ACH though without referencing the size of the house. However, where ACH is already greater than 0.75 a forced ventilation system is unlikely to be of use at controlling condensation and instead insulation or heating are better remedies. Seven out of eight houses studied in NZ in 2010 had an ACH (corrected for ventilation factors) of 0.75 or greater. The presence of forced ventilation systems has been shown in some cases to actually increase the humidity rather than lower it. By displacing air inside a dwelling with infiltrated air (air brought in from outside the dwelling), positive pressure ventilation systems can increase heating (in winter) or cooling (in summer) requirements in a house. For example, to maintain a 15 °C temperature in a certain dwelling about 3.0 kW of heating are required at 0 ACH (no heat loss due to warmed air leaving the dwelling, instead heat is lost due to conduction or radiation), 3.8 kW at 1 ACH and 4.5 kW are required at 2 ACH. The use of roof space for heating or cooling was seen as ineffectual with the maximum heating benefits occurring in winter in more southerly regions (being close to the South Pole in these southern hemisphere reports) but being equivalent only to about 0.5 kW or the heating provided by about five 100 W incandescent light bulbs; cooling effects in summer were similarly small and were more pronounced for more northerly homes (being closer to the equator); in all cases the values assumed that the ventilation system automatically disengaged when the infiltrating air was warmer or cooler (as appropriate) than the air already in the dwelling as it would otherwise exacerbate the undesirable conditions in the house.
   By the end of the day the slab has in turn warmed up, and now, as external temperatures decrease, the heat can be released and the slab cooled down, ready for the start of the next day. However this "regeneration" process is only effective if the building ventilation system is operated at night to carry away the heat from the slab. In naturally ventilated buildings it is normal to provide automated window openings to facilitate this process automatically.
  
  Section::::Thermal mass in buildings.:Use of thermal mass in different climates.:Hot, arid climates (e.g. desert).
   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 the past, water heating was more efficient for heating buildings and was the standard in the United States. Today, forced air systems can double for air conditioning and are more popular.
  
  Some benefits of forced air systems, which are now widely used in churches, schools and high-end residences, are
  
  BULLET::::- Better air conditioning effects
  
  BULLET::::- Energy savings of up to 15-20%
  
  BULLET::::- Even conditioning
  
  A drawback is the installation cost, which can be slightly higher than traditional HVAC systems.
   BULLET::::- Facilities for breeding laboratory animals. Since many animals normally reproduce only in spring, holding them in rooms in which conditions mirror those of spring all year can cause them to reproduce year-round.
  
  BULLET::::- Food cooking and processing areas
  
  BULLET::::- Hospital operating theatres, in which air is filtered to high levels to reduce infection risk and the humidity controlled to limit patient dehydration. Although temperatures are often in the comfort range, some specialist procedures, such as open heart surgery, require low temperatures (about 18 °C, 64 °F) and others, such as neonatal, relatively high temperatures (about 28 °C, 82 °F).
  
  BULLET::::- Industrial environments
   The furnace in utility core supplies heat to the main space through heating ducts, which are arranged along the base of the glass walls for maximum efficiency. During the winter the lack of overhangs provides maximum passive heat gain, and use of the original Koolshade panels was meant to minimize excessive heat gain in the summer.
  