Passive Solar Cooling Home

Discussion in 'Building a Net Zero Energy Home' started by Kassel Kuhn, Jun 8, 2017.

  1. Kassel Kuhn

    Kassel Kuhn New Member

    Jun 8, 2017
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    The house is at a reasonable altitude, so the summer temperature, out in the shade, is a comfortable 78 F, and the nights are close pleasant. It is a sweltering 100 F in the summer Sun, though.

    I have wood for heating in the winter, but not much electricity for cooling in the summer, so my intention is to design a house primarily for passive cooling, with enough insulation to retain the heat in winter once heated with a fireplace.

    I wanted your opinion on a departure from traditional construction for a Zero Energy Home.

    My intention is to design the house, not as a rectangle, but as an octagon, with one side each facing North, South, East, West, South East, South West, North East, and North West.
    This would be somewhat of a South-facing house, but not exactly.

    I’m living in an extreme climate, with summer peaks of around 100 F and winters of around 26 F.

    The summer night-time temperature drops to around 71 F, for difference of around 30 F between the day-time and night-time temperatures, so I would like to quickly dissipate the heat gained by the South-facing front at night to take advantage of the cool outside temperature. In winter, I would like to absorb the heat from the Sun for the night.

    The entire South-facing (South, South East, and South West) portion of the octagonal house, I intend to use only during the days in summer and only during the night in winter.
    My intention is to use a highly reflective and emissive roof for the South-facing front to reflect the summer Sun during the day, and quickly lose the heat at night. This room can have a moderate enough emissivity to radiate the winter sun in during the day.

    For all the rooms oriented somewhat South (South, South East, and South West), I could use windows to capture the radiant heat during winter and use reflecting shutters to block this heat during summer. These windows can also be opened at night during the summer, to quickly lose the heat to the almost 30 F night-time drop in outside temperature.

    The roof for the entire South-facing (South, South East, and South West) can be sloped and constructed from sheets of galvanized steel from the), so it reflects the heat during the day and dissipates it at night.

    For the entire North-facing, the roof can be flat to reduce the surface area and constructed from reinforced steel concrete (with a layer of insulating material) to diminish heat radiation through a thick and non-reflecting material and to enhance heat retention through the solar mass.

    The windows for the South-facing can be large and double-paned with galvanized steel shutters, on the outside, to block radiant heat during summer and allow the radiant heat during winter.

    The entire North-facing and even South East-facing can have relatively smaller double-paned windows to be left open during the summer to cool air in, and shuttered, on the inside, with galvanized steel shutters during the winter to diminish radiant heat loss.

    The intention is to situate the kitchen in the South which will receive peak summer heat only during noon, when my servants are taking their siesta. My children’s rooms can face East, so that it is only hot during the early morning when they’re away at school, and quite comfortable when they return because the kitchen would block the afternoon Sun. The guest room can West, so that it is hot only in the afternoon when the guests are away, and is comfortable during the morning and evenings when the guests are in the house. The dining room can face South East, so that it is comfortable during early morning, afternoon, and evening. The laundry room can face South West, so it is warm throughout the day, and maybe can even serve as a lounge during winter.

    The master bedroom can face North East, so it only receives the Sun for a very short time in the morning (I can take quilts during winter), and I can take my afternoon nap. The rarely used drawing room can be in the North, so it is shielded during the summer. It doesn’t matter if it gets unbearably cold during winter, because it would be used for a very short time. I can have another bedroom for my children in the North West, so it isn’t too uncomfortable at night or during winter.

    The lounge can be in center of the octagon, so it is shielded from the Sun during summer and insulated during the winter by the rooms around it.

    The attic on top of the lounge can serve as a day-time lounge during winter, when it catches ample of sun, and night-time living room during summer if it can dissipate quickly dissipate the heat gained during the day and even catch the cool summer night breezes.

    I want the attic to have large windows on all sides, kept closed in winter, to allow for the passage of radiant solar heat in winter and opened up, at night, in summer to facilitate the dissipation of summer heat.

    A small North attic-window can be fed with cold war, through a duct from the North ground-level, and a small South attic-window, heated by the Sun, can be opened during the summer day to create a cross-ventilation channel from the north to the South of the attic, with the hot air from the South-window flowing out and cold air from the ducted North-window flowing in. The windows on the West and East would remain shuttered during the summer-day to retain the heat gradient between the North and South windows for the cross ventilation channel.

    I can also have cross-ventilation ducts running from 170-feet under-the-ground, running at ground level through the house, from floor-level in the North, with small vents in each room for climate control, to roof-level in the South to create a channel of geothermal-air through the house. Since deep-earth maintains the same temperature throughout the year, this geothermal-air will cool the house in summer and warm it in winter.

    Another cross-ventilation duct, at roof-level from North floor-level to South roof-level, can work as an exhaust to suck the hot-air out. The roof-level duct in the South can be kept hair than the Winter Sun to have the exhaust automatically disabled in winter. It would still need air-sealing and insulation, at both ends, during winter.

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    Last edited: Jun 8, 2017
  2. Kassel Kuhn

    Kassel Kuhn New Member

    Jun 8, 2017
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    Both the geothermal air-pump and the air-temperature-differential exhaust would still need air-sealing and insulation, at both ends, during winter.

    I don’t have much faith in air ducts, or even in window-based cross-ventilation channels, because the quantity of air displaced is too little, the insulation and convention leakages are massive, and opening and shutting them is a hassle, so it might make sense to do away with these altogether, and focus solely on reflection, convection, and conduction processes for solar temperature control.

    Since, I’ll be having a sloping galvanized steel roof on the entire-southern portion of the house (for reflection during summer days, dissipation during summer nights, radiation during winter days, and non-utility, or limited utility with reflective windows and roof with a small heat source, during winter nights) and a flat reinforced-steel-concrete roof over the entire-northern portion of the house, I could I have the same galvanized-steel roof extended even over the entire northern concrete-roof as an outer shell to serve as a thermal buffer during both summer and winter.

    The central portion of the octagonal ground-floor roof would have to be 3-feet higher, at 14-feet, for it slope down to 11-feet at the sides. The attic can be 11-feet high, and perched on top of this central portion.

    I have used roofs at 11-feet for all rooms to allow for ample space for ceiling fans and ventilators, and the central roof at 14-feet to allow for the roof to slope down over the siding rooms. I have used sloping roofs for perfect drainage of rain water, for reflection of the sun during summer days, and for increased surface area for heat dissipation at night.

    The Northern portion of the house will use the Southern portion as a thermal buffer, the Eastern portion will use the Western portion as a thermal buffer, while the roof will use the attic as the thermal buffer.

    I also intend to take the floors around 3-feet below the ground level for insulation and geothermal climate-control. Taking the floors deeper down would deprive me of the windows and make climbing the stairs a hassle. With floors, deep, at 3-ft, I could still have ample of height for the windows to capture the winter Sun, and provide me with a scenic view of the lawn.

    The floors, I intend to make of marble or stone, for the Southern portion, to couple the floor to geothermal earth and to dissipate heat at night. For the Northern portion, I intend to use ceramic tiles to serve as a thermal mass and an insulator.

    The walls of the entire Southern-portion can be made from stone, so they conduct heat during the day in winter and quickly dissipate heat at night in summer. I’ll be using this portion only during the day in winter and only during the night in summer.

    The Northern portion can have walls made out of brick or concrete blocks, complemented with a layer of an air channel or an insulation material inside the walls, to prevent conduction/radiation and provide thermal mass to retain heat during in winter and retain cold during the summer.

    I intend to have all doors opening to the outside to be double doors, preferably both opening to the outside to limit the air-draft coming in or the outer door opening to the outside but the inner opening to the inside to conserve space between the two doors or even the inner door as a sliding-door (which is somewhat of a hassle to slide open).

    The windows, of course, will be all double-paned to permit radiant heat in during winter, inhibit conduction to the atmosphere through an air-gap between the two, and shuttered, with galvanized steel sheets, during the day in summer and during the night in the winter to block radiant heat. The windows in the Southern-portion can have the shutters on the outside to block the Sun, while those in the Northern-portion can have shutters on the inside to hold the heat in during winter.

    The climate, around my home, is extremely hot during the summer and uncomfortably cold during the winter, so all choices have trade-offs, and the best choice isn’t optimal for either season, but moderate during both, with a greater bias towards passive solar cooling in unbearable summers.

    I gave geothermal heating and cooling a great deal of thought, but opted against it because the piping and the digging is a hassle and the equipment is too expensive for disproportionate savings. I even pondered using my water tank or swimming pool as the heat-exchanger for the heat pump, but the piping is a hassle that could turn into a disaster if there were to be even mild leakages.

    I intend to use solar panels for electricity generation, during the day, and wind-turbines, at night, because I’m averse to having to replace the batteries every year.

    A parabolic solar-reflector to complement the electric power, with heat-power directly supplied to the compressor, is a better alternative to geothermal power because you primarily need cooling only during the day, since the nights are quite comfortable.

    One could also use solar-mirrors to heat the thermal mass during the day in winter.
  3. Kassel Kuhn

    Kassel Kuhn New Member

    Jun 8, 2017
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    Cooking is a major hassle at a location with no electricity or gas, but there are solar cookers for those who have early suppers. These solar cookers use mirror and lenses to heat and a thermal mass to retain the heat into early night, but I favor the condenser of the heat-pump to everything when it comes to heating a space, heating water and cooking food, and the evaporator of the heat-pump whenever you want to cool a space, liquid, or anything. You can have a coil from the condenser of your air-conditioning unit supplied to the kitchen and turned on and off through a value. You could also use a fluid/refrigerant directly heat by mirrors and lenses to do your cooking. This hot refrigerant/fluid can be stored for the night inside an insulated thermal mass.

    Communications isn’t an off-grid issue if you’re living at a considerable altitude because you do receive ample cellular coverage, but you have an HF (6m-180m) radio voice and data/internet ( back system and two satellite ( and voice and data backup systems.

    The gist of all this is that a large portion of the summer heat is gained through the roof, so the emphasis should be to prevent this gain through reflection and insulation during the day and to lose it through dissipation at night. Most of the heat gained in winter is through the Southern windows, so the emphasis should be to maximize this, prevent it from occurring in summer by placing the windows below the summer Sun, and retain it at night through insulation, such as reflective pull-down shutters over the windows, reflective stone walls, reflective galvanized-steel roofs, and insulation and heat mass below the reflective roof, behind the steel shutters, and over the reflective roof in the Southern portion of the house. The Northern portion doesn’t receive much sun, so the emphasis for wall and roof insulation would be to use insulation on the outside to prevent heat from going out, while retaining heat in the thermal mass on the inside of the insulation. The Southern portion would use wall-insulation on the inside, so the thermal mass can store the summer heat outside of the insulation, keep the inside cool, and then lose it to the outside environment at night. The Southern-roof would have no insulation, so it can gain heat during the winter days, when it will be only used during the day, and lose it night in summers, when it will be only used during the night.

    The air-conditioning can have the condenser coils running deep through the earth for geothermal heating in winter and cooling in summer, or the condenser coils can run through the water-tank or the pool for water-cooling only in summer. This air-conditioning system could also heat the water to provide you with hot water both in winter and summer. If you’ll just be using the air-conditioner during the day in summer, the refrigerant can be heated by the Sun either through parabolic or paneled mirror or glass lens reflectors. You can have a heating chamber in lieu of the compressor during the day, and the compressor can only be used at night when there is no sun. This can work both during winter and summer.

    One could also have a Sun-driven, duct-based, geothermal cooling system with pipes from the outside on the North going 100-feet into the ground, turning around in a loop, coming out through South for the winter Sun to heat the South-side of the pipe and turn the pipe into a pump with heat from the North going down deep into earth, getting cooled/warmed, and the excess coming out on the South after it has been distributed, at the chair-level, through vents in all the rooms. You can similarly have an exhaust with an inlet at the ground-level, outside the back of the house in the North, and he outlet heated by the Sun in the South, with the hot-air rising out through the South and the cold-air sucked in through the North.

    I neither favor ducts nor channels because unwanted leakages are massive and desired heat transfers are insubstantial, but if you want to use them, you can have them shut and open through a pneumatic instead of an electrical or a mechanical/hydraulic system. The air-compressor could use parabolic or paneled mirrors or glass lenses to heat the air and compress it, the compressed air can be forced behind a valve to permanently store it when the tank cools down with the Sun-going down, and this air could then open and close locks and open and close vents and valves for the air-circulation system. The outlet and inlet pipe/valves would have to be on the slanting portion of the roof and slightly higher from the ground at the back to prevent these from sucking rain-water and these have to barely stick out of the Southern front-roof and Northern back-wall for these to not lose heat to conduction/convection. Furthermore, their shutters/lids, at both ends, need to be well-insulated. You’ll have a computer coupled to sensors and transducers opening and shutting these, turning the air-conditioning on and off, and switching the lights. The computer can manipulate software-controlled switches through a low-energy RF/AC or wireless home-network with each switch assigned an IP.

    You can also use mirrors or lenses to directly heat parts of the house in winter or to store the heat energy in a thermal mass, like a blend of earth and sand, for the night by heating it during the day.

    Finally, you’ll have parts of your roof covered with solar panels to block the summer sun, but not the winter Sun, which travels low and mostly comes in through high Southern-windows.

    I’m running out of time, so please exhaustively critique my notions in order us to explore the ideas further and improve upon the concepts presented.
  4. Arvind Vermani

    Arvind Vermani New Member

    Jan 18, 2018
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    I know this was some time ago and you said that you were running out of time. However, if you are still interested in discussing this further, I'll be vey happy to collaborate. Feel free to send me a private message

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