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Types of Systems |
Local Electric – Small electric heaters or air conditioners are the most inefficient method of heating or cooling. They just guzzle energy. It is better to have one central system that feeds throughout the building.
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Heat Pump – Air conditioning units can be placed on roofs, in windows, outside, in attics, or free standing in rooms. Since they work by separating temperatures into hot and cold extremes, they can provide both cold and hot air. But heat pumps on their own are very inefficient.
Stove – Gas stoves are more efficient than electric. Depending on the government’s cumbersome regulations, wood stoves are a simple but often overlooked option. They are more efficient than fireplaces. |  |
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Forced Air – Air conditioners are often combined with natural gas stoves in HVAC systems to provide cooling and heating. They blow air through ducts throughout the building.
While they are more efficient they can have their drawbacks. The air ducts collect dust, are noisy, and provide uneven heat. They really should not be considered a default solution for heating or cooling a building. Swamp Cooler – The swamp cooler uses evaporation to cool a space. Air is rushed through moisture, cooling it down, and is then distributed through the building. This is a low cost option but can often break down and require upkeep. For this reason it is becoming less popular. |  |
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Radiant Heating –
Electric cables or hydronic pipes heat the floor or free-standing radiators in radiant heating systems. They provide quiet, cost effective, and even heat. Hydronic systems, which use propylene glycol in pipes, are popular but not really a better choice than electric cables because they require constant upkeep, could be dangerous if contaminated, and have a more difficult transferring heat. |  |
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A separate cooling system is required. Ceiling fans are a good low-cost option. The fans could also circulate the warm air from the radiant heaters and make the heating more efficient.
Solar Heating – Solar roof panels can be used in conjunction with radiant heating. Hydronic pipes lead to the solar panels for pre-heating before returning back to the boiler. Or the solar system runs through a heat exchanger to give a boost of heat to heater. |  |
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Geothermal – Geothermal pipes are another method for pre-heating a heating system, but they have the added advantage of being able to pre-cool as well.
The ground below permafrost depth stays a fairly constant temperature. Propylene glycol can shed its heat on really hot days or gather heat in freezing outside temperatures by pumping it through the ground and then sending it into a heat exchanger. Lakes and other water features could also be used. |  |
Where To Locate Heating/Cooling Systems
- Away from fumes – Serious health problems arise from intake air ducts sucking up car exhaust. Keep them away from automobiles, flus and chimneys, dust and clogging leaves, etc.
- Temperate location – Air systems are often placed on roofs because that is out of the way. But these roofs can reach very high temperatures in the summer and it does not make sense to draw in this hot air into an air conditioner. Instead find a shady, planted place that won’t be too hot in the summer (for cooling systems) or too cold in the winter (for heating systems).
- Away from people – These HVAC machines can be noisy. They are often placed in basements or have fences built around them to keep down the annoying sounds. Basements are also a handy location because heat from the heater can more naturally rise up and heat from the summer does not hamper air conditioning in this cool space.
- Under windows, NOT in center of room – It is mistakingly assumed that a stove in the center of a room will give the most even heat, but this is not true.
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Convection moves the air up and out to the wall. It meets the cool wall or window and sheds its heat. Cooler air is pulled from the wall into the room and feeds the stove. The draft this creates is cold and could be even worse than if there were no stove at all. A heat source under the window or at the bottom of the wall uses convection to its advantage. Heat fills the room and is pulled back, recycling the same air to feed the stove. Less heat leaves the building. |   |
How to Design a Duct Layout
- Separate into zones – The most important consideration is how the rooms are partitioned. Massive amounts of energy can be saved by heating only the rooms that are most used in the winter. When layout out ducts consider zones that are used in the summer or winter and provide seperate supplies, or close certain vents according to seasons. Traditional homes in Tibet use temporary tapestries to section off spaces within rooms. Provide temporary partitions for these sub-spaces.
- Ceiling and low vents – In determining which vents to use by seasons, it is helpful to have return vents that are high up and vents that are low to the floor. The warm are that rises is best to get rid of in the summer but in the winter it should draw from the cool air low down.
- Simple straight runs – To avoid noise and opportunities for dust accumulation, avoid turns and complicated duct stretches.
- Evenly spaced – Typical bedrooms need only one supply vents. Moderate sized rooms should have two. Space them evenly around the room and consider how convection will move that air around when it reaches walls and windows. Also consider where furniture will be placed so vents don’t get blocked.
- Operable – Use vents that can be opened and closed. It is okay to have more vents spaced around a room than you need so that the occupant can pick which vent works best at any time. Make it easily accessible for cleaning and repairs to be made.
Using Natural Breezes To Heat Or Cool
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It is easy to create a natural draft to help cool a building.
Find out the direction of the prevailing wind. Consider site elements that direct the breeze. Remember, a breeze needs both an inlet and outlet. You need a path for the breeze to enter the building and to exit. Pre-cool the air at the inlet, perhaps with trees or shady overhangs. Plan out a path for the air to travel, and provide an outlet to a warmer space. The warmth will help suck out the air from the room. Use operable windows– Windows that occupants can open are always better. Wind tunnel effect – Traditional frontier homes had porches between two buildings. Air hits the buildings, squeezes into these breeze ways, speeds up, and blows out into large low-pressure spaces. Consider the prevailing wind direction and site elements for how the air can get funneled into and out of a building. Use natural breeze paths and temperature zones to boost the pressure differences. Thermal mass, for example, can help cool the air as it enters the breeze way. |  
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Recapture Heat From Waste Water
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Air systems reuse air from the building to preserve heat, so why shouldn’t hot water heaters do the same thing? A simple copper pipe coils around the waste water pipe to grab much of its heat before heading into the water heater. This pre-heats the incoming water and saves considerable energy. Most waste water heat is from showers, so many recapturing systems focus exclusively on shower drains. Heat gets lost exponentially as the waste water drains out of the building.
The effectiveness of this sytem depends on:
To help with this, it is important to use a drain that spreads water out to the edges of the pipe. Have drainage holes only at the rim and a spreader that pushes, maybe spirals the wall outward. A gently sloping entrance drain helps keep the water from flowing into the middle. Maximize how much of the water sticks to the edge of the vertical pipe. As the waste water bends to a horizontal direction, the incoming water pipe can attached to the bottom where the waste water settles, with aluminum tape wrapped around them. This increases the exposure time between the incoming copper pipe and waste water. Avoid grey water basins as they need filtering. The copper coil system is easy and should take no upkeep. |   
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© Benjamin Blankenbehler 2013
