heating AND COOLING SYSTEMS FOR new homes

Heating and cooling accounts for almost half of the energy costs of typical American homes (about 46%, 2011 EIS). Reducing them is a top priority, very difficult to achieve in existing homes.

So, if you are going to build a new home, seize the opportunity; it’s a lifetime chance. You will save many hundreds of dollars during the lifetime of your house.

You can reduce your heating and cooling bills by installing high-performance appliances and well designed ducts, as short and as straight as possible. That's an approach, that can provide very significant energy savings.

But if you live in a cold climate and want to reduce your heating (and cooling) bills by as much as 80%, you need another approach. You can't rely on central ducted heating (and cooling) systems... Central ducted furnaces and boilers, and central air conditioners, are too energy-intensive.

The only way to replace them, in cold climates, is to build a modest sized and compact home, with a very good design and high levels of insulation and air-tightness. That will reduce your energy needs to a much smaller fraction, allowing other types of heating and cooling. That's a second approach (the Zero Energy Buildings one).

Below, we present variants of these two strategies...

Heating

Option 1: gas space heaters or Mini-Split heat Pumps

New ductless gas and electric space heaters (especially wall ductless gas furnaces or mini-split heat pumps) are not just for moderate climates. They can also meet the heating needs of super-insulated homes, in very cold climates (Zero Energy Homes).

In other words: you need to have a compact and relatively small home, highly and carefully insulated; you need a home with high levels of air-tightness, good orientation to the sun (for heat gains) and high-performance windows properly sized... Something close to Passive Solar Houses.

Heating Option 2: Electric heating

Electric heating is typically expensive to run. But it is cheap to install and to buy, and doesn't pose safety concerns, which makes it a good option not only in climates where heating needs are low but also in homes that are sized, sited, designed, insulated and equipped according to high-performance standards.

Only in such conditions electric heating becomes a viable option for cold climates, especially mini-split heat pumps.

Heating Option 3: a small furnace

In some cases, a small furnace, conveniently installed and with a short and straight duct system, can provide significant energy savings.

That's the best option in very cold climates, in very large homes, or homes with conventional levels of insulation and without the design and the features required by very energy efficient homes. That’s a compromise solution, below the standards of green building.

As mentioned, the duct system should be short and straight, and located within the thermal envelope of the house; the supply registers should run along interior walls and the equipment should not be located in attics, crawl spaces, or garages.

Heating Option 4: conventional central ducted systems

In cold climates, large homes with low levels of insulation and a poor design may need a central ducted system.

If you are going to install a furnace or other central heating system, avoid oversizing, consider a multi-stage model and use 'zoning' and smart thermostats and ducts with dampers (or automatic valves on the hot-water radiators/baseboards).

Over-sizing is very common and a cause of energy waste, and should be avoided at all costs. Discuss it with the contractor.

Also locate the equipment and ductwork inside the home's conditioned space; that’s very important for energy savings and efficiency.

See: Furnaces Guide

Heating Option 5: hydronic systems

Heating with boilers or any hydronic system should follow the principles listed above.

Do not oversize, and keep the equipment and the ducts inside the conditioned space. Consider super-insulated and very air-tight homes.

Systems like hot water radiant heating, though highly praised and able to provide high levels of comfort, are unsuitable for low-energy homes, with low heating requirements. . Hydronic systems are typically too expensive and designed for large-energy-inefficient homes.

See: New Efficient Boilers & Hydronic Systems

Cooling

Option 1: without central air conditioners, in hot climates

Homes with good design and properly constructed may not need central air conditioners, even in very hot climates. Most people in tropical climates manage without air conditioning, and that's more than just lifestyle, low income or habit (though that counts).

If you live in a hot climate and building a new home, consider carefully its design, layout and overhangs but also the type of glazing, window films, reflective roofs and insulation, tree shading, sun-protection and natural ventilation. See, for details: Natural Cooling & Energy Savings

See: Air conditioning in hot climates and Guide To Cooling with Air Conditioners.

Cooling Option 2: cold and moderate climates

In cold and moderate climates, well-sized overhangs, natural ventilation and proper summer landscaping and circulation fans can reduce mechanical cooling needs to very low levels.

The need for cooling can also be reduced through the low-energy rules used in heating strategies, especially high levels of insulation and air-tightness...

Cooling Option 3: ductless air conditioners

If you do need mechanical air conditioning, consider the use of ductless air conditioners and mini-split air conditioners. They are a lot less expensive to run and to install than central air conditioners.

 

 

 

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