Last Updated on October 9, 2022 by Barry Gray
Heating is a significant consideration when planning homes. Some older houses were not designed with heat efficiency in mind. If you live in one of these old buildings, you may be considering upgrading the heating. It is critical to know how heat is lost in a building so that steps can be taken to prevent heat loss and use heating most effectively.
There is no definitive answer to whether more heat is lost through the ceiling or the walls. The construction materials influence the amount of heat lost as each has its own specific heat capacity. Seasonal variations can also affect the amount of heat lost through the ceiling and walls.
Understanding heat loss is critical to insulating your home and saving on your energy usage. Many people are surprised by the way heat is lost from a home. Many blogs categorically state that most heat is lost through the walls, while others claim it is through the roof. Establishing the actual heat loss areas is more complicated than making sweeping claims.
Each Home Must Be Evaluated To Determine Where Heat Is Lost
Each house or building is unique in terms of its construction material, location, and design. These factors all influence the way that heat will be lost.
Construction Materials And Techniques Effect Heat Loss
Every material used to construct houses has a specific heat capacity that will influence how much heat is lost. It is critical to understand this concept if you are designing a home as it will affect heating plans. So what is specific heat capacity?
Specific heat capacity is the amount of energy required to heat a material by one degree. Material with a high specific heat capacity heats up slowly and gradually cools down or loses heat.
Bricks have a higher specific heat capacity than wood. A masonry house will have less heat loss through the walls than a clapboard or log home.
Bricks and stones are described as having high thermal mass, which is the ability to absorb, store and release heat. A warmer wall would lose less heat to the environment. Cob and wood have low thermal mass. Walls constructed of these materials would leak heat from the home. The width of the wall would also influence the rate of heat loss. A log cabin would lose heat slower than a clapboard house.
Walls may be built as solid walls or as cavity walls. Cavity walls have a layer of air between two separate walls or layers. These walls are sometimes described as hollow walls. The two layers on either side of the air may be constructed from brick, stone, or wood.
The air cavity between the two layers acts as a form of thermal insulation. Cavity walls, therefore, lose less heat than solid walls. Cavity walls are easy to insulate and may be built with insulation material filling the air between the two layers.
Roofing materials also vary and influence the amount of heat lost through the ceiling. Metal roofs absorb less heat than asphalt shingles.
Metal roofs reflect a lot of the light that strikes the surface, giving them a low thermal mass. As a result, metal roofs would cool your house in summer but also lose heat in the winter months.
Asphalt and slate shingles have a high thermal mass, and less heat would be lost through the ceiling in these homes. Thatch is not a good heat conductor and would keep your home cool in summer, and there would be minimal heat loss in winter.
How Does Design Effect Heat Loss?
Houses may be designed to minimize or maximize heat loss, depending on the climate in which you live and your preferences.
High ceilings or vaulted roofs generally lose more heat than low ceilings. The expanse between the ceiling and the roof is much smaller in high ceiling designs.
The diminished air space allows heat transference to occur more easily between the ceiling and the roof material. Thus, the heat is lost through the roof into the atmosphere. Low ceilings usually have a bigger space between the roof and ceiling and lose less heat.
In high ceilings, the heat rises to the top of the structure leaving cold air to flow into the lower regions of the room. The room will feel much colder.
Poorly designed attics with no insulation or high ceiling buildings may lose up to 69 % heat through the ceiling and roof. Only 5 % of the heat will be lost through the ceiling in a block of flats. The heat is prevented from escaping by the flat above.
The design and correct fitting of windows and doors are crucial to heat loss. 38 % of the building’s heat can be lost through cracks around the doors and windows. This increases the total amount of heat lost through the walls.
Location Effects Heat Loss
A house located on the side of a hill that experiences frequent icy winds will have a more significant heat loss through the walls. The wind blows on the walls causing a drop in temperature on that side. This is transferred throughout the house.
This phenomenon is often seen in houses built on land overlooking the sea or large bodies of water. Night breezes bring cool air from the ocean to the land and cause buildings to lose heat.
A home built in a protected area with little to no wind will have a reduced loss of heat through the walls. In this instance, most of the heat will be lost through the roof.
How Do I Determine Where Heat Is Being Lost?
The best way to determine where heat is being lost in your home is to consult an energy or heating company. They will perform a home energy or heat audit using a thermal scanning device.
This device will allow you to see the warmest and coldest areas of the home and where heat is escaping. This invaluable tool enables you to maximize insulation for your home and can help you save money on energy bills.
Many people waste a lot of money double glazing their windows to increase the heat in their homes. The problem may be inadequate insulation on the roof or walls. Double glazing will make an insignificant difference in heat retention if the heat escapes through the wall or ceiling.
It is difficult to say where the majority of a home’s heat is lost. Heat loss is dependent on design, construction materials, and location. It is best to get an energy professional to help you determine the sources of heat loss in your home.