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Rooms Too Hot or Too Cold

Overview

It is common to feel uneven temperatures throughout a home. These temperature differences make particular rooms feel drafty and cold or stuffy and hot, and there are ways to solve these problems.

Every room in a house needs different amount of heat depending on the number of exterior walls and windows, the amount and quality of the insulation, room size, etc. Most duct systems are designed to deliver the same amount of air to each room, resulting in some rooms that are too hot or too cold. This common problem can be solved by considering the home as a system.

Contributing Solutions

house as a system To solve the problem of uneven heat in a house all contributing root causes must be addressed. As with many systems the whole is greater than the sum of the parts. For example, installing a properly sized and efficient furnace and sealing the ducts will do more to help keep even temperatures throughout the house if they are done together than if they are done separately. Here are the main things to be considered in a house which feels too cold:

Reduce the heating or cooling needs in rooms which are more exposed to the outdoors by having more windows or exterior walls
Help the duct system deliver the appropriate amounts of cool or warm air to each room in the house, by reducing air resistance in the ducts (static pressure) and by making sure each room gets the right amount of air (air balancing)
Make sure the heating and cooling systems are working properly and well adjusted, since less heating and cooling will be needed overall when exposed rooms are well insulated and air sealed and filters are cleaned
Make sure the thermostat isn’t overly exposed to hot or cold temperatures by plugging the hole behind the thermostat and make sue it is away from direct sun or airflow from the registers

Building Envelope and Duct Solutions

These solutions should be addressed first to improve a home’s ability to retain warm or cool air and to assure that the ducts are delivering warm or cool air to the rooms which need it instead of wasting it in the attic or crawlspace. The building envelope and duct system need to work together with the heating and cooling system to make sure that some rooms are not too hot or too cold.

Air Sealing: A tight building envelope makes insulation more effective and helps stop entry of cool air from below the house and warmer air being pulled up; this “stack effect” is partly behind the common problem of rooms upstairs being hotterthan rooms downstairs.
Insulation: Added insulation will be much more effective in an air sealed home. Insulation will help stop accumulation of drafty or stuffy air in a room which is particularly exposed to heat or to cold.
High Performance Windows: Well engineered and well installed windows can add additional insulation and air sealing
Duct Sealing: Properly sealed ducts will deliver more hot or cold air to where it’s needed instead of letting it leak into the attic or crawlspace, making a big difference for rooms furthest from the furnace or air handler. This effect will be compounded in a home which can maintain constant temperatures thanks to air sealing and insulation.
Air Balancing: A well balanced duct system will eliminate the problem of some rooms getting too much or too little warm or cool air from the system. It is only really useful to air balance a well sealed duct system and well sealed and insulated rooms will better hold warm or cool air that is delivered to them.

Air Sealing

Air infiltration in typical houses is roughly split:

1/3 floors, walls, and ceilings
1/3 ducts, vents, plumbing penetrations, and electrical outlets
1/6 windows and doors
1/6 fireplace

Gaps, cracks, and small holes in all of these areas must first be sealed for insulation and heating and cooling systems to be effective. Air sealing addresses uneven heat between different rooms in a house by eliminating drafts and temperature differences in the home which result from the stack effect, where cold air enters the home from beneath and hot air exits from above.
Air sealing from above reduces the force of the stack effect and sealing from below raises the pressure plane (under which air gets pulled into the house), improving indoor air quality and saving energy during the cooling season.[+] MORE

Insulation

In general, more heat is lost through walls, floors, and ceilings (which are generally poorly insulated) than through windows; since insulating these areas is generally more cost-effective than replacing old windows in an existing home, proper insulation and air sealing should come first. Properly installed insulation addresses uneven temperatures by minimizing temperature variability indoors and helps keep rooms warmer in the winter and cooler in the summer, particularly in rooms exposed to heat gain (with a large proportion of exterior walls and windows) or to cold (such as a basement or a room over an uninsulated garage or crawlspace). [+] MORE

High Performance Windows

High performance windows save money by insulating the home from conductive or radiant heat loss or gain, as well as by protecting furniture and fabrics from fading. A poorly insulated window actually radiates heat toward the room when it is very hot outside and draws heat out of the room when it is very cold outside. This makes sitting near such a window uncomfortable because it feels drafty in the winter and stuffy in the summer. Once a home has been well sealed and insulated, high performance windows can address uneven heat in particular rooms which are too hot or cold by stopping heat from accumulating or flowing through a large or particularly exposed window. High performance windows such as Serious Windows also provide a tight air seal to reduce air leakage in the building.A more cost effective alternative to window replacement is installation of a reflective window film such as 3M Prestige or Night Vision window film. [+] MORE

Duct Sealing

Most duct systems have a more or less widespread problem of air leaks, from many small holes to several-inch-wide gaps between duct joints and even disconnected ducts. Duct sealing, which is among the most cost effective of home performance retrofits, prevents conditioned air from leaking out of ducts and crawlspace or attic dust from infiltrating the home. Duct Sealing can help bring temperatures in particularly uncomfortable rooms in line with the comfort level of the rest of the house by eliminating air leaks and delivering the correct amount of air according to the design. Well sealed ducts will be better able supply sufficient heated or cooled air to all parts of the house, and maintain better indoor air quality through reduced imbalances within the house, reducing crawl and attic contaminants sucked into the HVAC system. [+] MORE

Air Balancing

Air balancing of the home and duct system consists of using instruments to measure and adjust air flow in the duct system and registers to assure that conditioned air is evenly distributed throughout the home and that there are no pressure imbalances which might cause infiltration of outside air or loss of conditioned air. Air balancing can help fix rooms that feel much colder or hotter than the rest of the house by assuring that the appropriate proportion of conditioned air is delivered to each room in the home, eliminating the need for supplementary fans or heaters in certain rooms. This may include zoning the duct system which allows different regions of the home to be heated differently. [+] MORE

Heating and Cooling Solutions

It is common to only think of a furnace when considering improving or replacing a home’s heating system. However, heating and cooling systems work together with the building envelope and duct system to deliver and retain warm and cool air to the home. For example, good insulation can be considered part of the heating system since heat that it retains is heat that the furnace does not need to generate. High efficiency heating and cooling systems such as Energy Star furnaces and air conditioners can cost less to run, but they will be most effective at delivering comfortable temperatures throughout the house when properly sized and operating in conjunction with a well sealed and insulated building envelope and a duct system with minimal leakage.

Programmable Thermostat: If the thermostat is exposed to heat from the sun or cool drafts, it will either under or over heat the house, since the temperature at the thermostat will be different from the rest of the house.
High Efficiency Gas Furnace: A properly sized, more efficient furnace installed with a well sealed and insulated building envelope and duct system and engineered registers will efficiently deliver heat to the right places increasing efficiency and comfort by more thoroughly mixing air in particular rooms and throughout the house. A right sized furnace is one that runs continuously on the coldest day of the year.
Hydronic Forced Air Heat: This alternative to a furnace can deliver more even temperatures in rooms and throughout the house by operating on longer cycles at lower temperatures (than furnaces), thereby mixing air of different temperatures more thoroughly and delivering heat more constantly and avoiding temperature fluctuations.
Radiant Hydronic Heat: Radiant heat can address the issue of rooms that are difficult to heat once they are well insulated by delivering different amounts of heat to different rooms by using zoning. Since they heat from below and do not need to mix the air, radiant floors can be great for areas with high ceiling and large volumes of air such as atriums and vaulted ceilings
High Efficiency A/C: A smaller, more efficient air conditioner installed with a well sealed and insulated building envelope and duct system will efficiently deliver cooling and dehimudification to the right places by more thoroughly mixing air in particular rooms and throughout the house.
Mini Split Ductless A/C: Once they are well insulated, rooms that are overly cooled or difficult to heat can receive varied amounts of cooling with these air conditioning units, which are great for heating or cooling rooms in a house that are separated or inaccessible to the primary HVAC system. Individual head units can be placed where needed without the need for ducts.

Programmable Thermostat

A programmable thermostat must be installed in a central location which reflect the average temperature in the house; otherwise it will turn on the HVAC system on too much or not enough. When programmed to reduces heating or cooling at night or when the home is unoccupied, a programmable thermostat can also save money.[+] MORE

High Efficiency Gas Furnace

The highest efficiency Energy Star furnaces are 10% to 20% more efficient than other furnaces. An inefficient furnace, or one that is undersized, may take a long time to heat up and may not be able to deliver enough heat to larger rooms in the home. A furnace which is oversized (a common occurrence) may heat up so quickly that it doesn’t run long enough deliver warm air to the furthest reaches of the house. A correctly sized and calibrated system will deliver the right amount of heat to the right places in the home, helping to deliver the right amount of heat to each room with extended run times. It is especially important to first improve the building envelope and duct system because doing so will generally mean a smaller furnace (which burns less fuel than an equally efficient furnace of a larger size) will be appropriate to heat the house. [+] MORE

Hydronic Forced Air Heat

Hydronic forced air uses heated water to deliver heat to the air duct system as an alternative to a furnace. In addition to greater efficiency in zoned applications, hydronic forced air can attain even higher total efficiency than the best Energy Star furnaces by combining space heating with water heating. A correctly sized and calibrated hydronic forced air system typically delivers more constant even temperatures than a traditional furnace. This can help address problem rooms which tend to be too hot or too cold compared to the rest of the home. [+] MORE

Radiant Hydronic Heat

Radiant heat provides heat by circulating hot water through coils under the floor or through a series of baseboard radiators. Radiant heat can complement a forced air system by delivering constant heat to hard to heat rooms far from the duct system and rooms where warm floors are desirable, such as bathrooms or basements; a radiant system can also deliver even temperatures throughout the home on its own by using zoned valves which deliver different amounts of water to different zones as needed. [+] MORE

High Efficiency A/C

Replacing an old air conditioner with an Energy Star unit can offer increased comfort and lower energy costs when correctly sized and installed in a well insulated home. It is especially important to first improve the building envelope and duct system because doing so will generally mean a smaller air conditioner (which uses less electricity than an equally efficient air conditioner of a larger size) will be appropriate to heat the house. A correctly sized and calibrated system will deliver the right amount of cooling to the right places in the home, and may be combined with a zoned duct system. By staying on longer and cycling less often, it will increase efficiency and comfort while removing more moisture from the air. [+] MORE

Mini Split Ductless A/C

Mini split ductless air conditioning avoids duct losses and provides easily controllable zoned cooling from one compressor. A small individually adjustable head unit can be installed in each room. These units can be particularly useful for houses which need different amounts of cooling in different rooms, such as a south facing room with a large window and a well shading north facing room with small windows. [+] MORE

Important Disclaimer

Product examples are for informative purposes only and mention of any product does not constitute a recommendation or endorsement of any product.

Recurve – Home Energy Audits & Green Remodeling / Construction Services – formerly Sustainable Spaces