House Energy Site

Home ducts & energy improvements

Leaky and un-insulated home ducts, poorly designed, can add hundreds of dollars to your annual energy bills.

Leaky Ducts: An Energy Calamity
Ducts leaky

Yes. That hidden and unnoticed network of tubes in the walls, ceilings or floors, carrying the air from your home’s furnace or heat pump or AC to the several rooms, can be a big energy waster.

Leaky and un-insulated ducts add hundreds of dollars to the bills of homeowners with central heating and cooling systems. The Department of Energy of the USA estimates at $160 per household/year the energy losses due to them, which multiplied by the 160 millions of American households gives 256 billion dollars per year, just for the USA.

See: Duct Sealing and Insulation Costs and Payback

technicianProblems With Ducts

Leaky ducts are also responsible for a large amount of energy waste through cracks and openings in the home’s shell, due to the pressures that the air coming out of supply ducts or entering into the return ducts put on the envelope of the house – which, in turn, is a cause of drafts and air dryness and air stratification (often attributed to equipment malfunction, but in fact due to problems with ducts).

Besides, leaky ducts can also be a source of unhealthy indoor air. Radon, CO and other pollutants in the basements, attics, crawl spaces and garages - where the ducts are often installed - can enter into your living space through leaks in the ducts.

Similarly, condensation on the interior inside of the ducts, due to lack of insulation, may lead to mold and mildew growth and ultimately to poor air quality.

Duct Problems

Ducts ClipDuct Sealing and Insulation

If your ducts are running in a garage, basement or attic, leaks in them are probably responsible for a part of your heating and cooling bills. Sealing them should be a priority.

And the same is valid for duct insulation; without proper insulation heat will flow through the walls of the ducts both in the winter and the summer, increasing your energy bills. Duct insulation may not be as critical as duct sealing, but it is also one of the most cost-effective energy improvements that you can carry out in your home.

Duct Sealing
Duct Insulation
Sealing Duct Air Handlers, Boots and Elbows

Duct Tapes, Mastics and Fasteners

Duct tapes can be useful to seal holes in the air handler and cabinets, or for temporary holding and bundling. But duct tapes tend to fail quickly.

Modern mastics - which do not use petroleum as a solvent base - are a much better sealing product.

Duct Mastic
Duct Tapes
Duct Fasteners

Clip ductsDesign, Type and Length of the Ducts

Problems with ducts go deep; they may involve their design, type, size and length...

Your duct system should be as straight and as concentrated and as short as possible. And you should prefer round, rigid metal ductwork...

Duct Type, Size, Length

Ducts for New Homes

The most energy-efficient way to deliver warm or cool air to your rooms is by using short and straight runs (or by using ductless systems).

Curves and 90º angles should be avoided. And the ducts should be located in the thermal envelope of the house.

To allow a short ductwork, you need high levels of home insulation and sealing, and good home design.

Duct Systems for New Homes

In New Homes, Consider Ductless Systems

If you are building a new home, you may not need a ducted heating (or cooling) system, especially in moderate and hot climates.

Building a New Low-Energy Home


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VideoOur Videos about Ducts

Ducts Part 1
Ducts Part 2




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