R-value (insulation)

src: usainsulation.net

In building and construction, R-value is a measure of how well an object, per unit of exposed area, rejects conductive heat flow: the greater the value of R, the greater the resistance, and so the better the thermal insulation properties of object. The R-values ​​are used in describing the effectiveness of insulation and in the analysis of heat flow across the assemblies (such as walls, roofs and windows) under steady-state conditions. The heat flow through the object is driven by a temperature difference (eg $Â\; Â{\displaystyle Â\; Â\; Â\; Â\; Â\; Â\; Â}$ _{Â Â Â Â Â Â Â Â Â Â T Â Â Â Â Â Â Â Â Â Â Â Â Â Â ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 2 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â - Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â T Â Â Â Â Â Â Â Â Â Â Â Â Â ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 1 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â {\ displaystyle T_ {2} -T_ {1}} Â Â} ) between the two sides of the object, and the R-value calculates how effectively the object rejects this drive: _{Â Â Â Â Â Â Â Â Â Â T Â Â Â Â Â Â Â Â Â Â Â Â Â Â ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 2 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â - Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â T Â Â Â Â Â Â Â Â Â Â Â Â Â ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 1 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â {\ displaystyle T_ {2} -T_ {1}}} divided with R-values ​​and then multiplied by the surface area of ​​the object side giving total the rate of heat flow through the object (as measured in Watts or in BTUs per hour). In addition, as long as the material involved is a solid solid in direct reciprocal contact, R-value is additional; for example, the total R-value of an object composed of several layers of material is the sum of the R-values ​​of each layer . Note that the R-value is a building industry term for what is in another so-called context? heat resistance per unit area.? Sometimes denoted RSI-value if SI unit (metric) is used.

R values ​​may be given to materials (eg for polyethylene foams), or for assembly of materials (eg walls or windows). In terms of materials, it is often expressed in terms of R-values ​​per unit length (eg per inch thick). The latter can be misleading in the case of low-density thermal insulation, where the R-value is not additive: its R value per inch is not constant because the material becomes thicker, but usually usually decreases.

The R-value units (see below) are usually not stated explicitly, so it is important to decide from the context of which unit to use: R values ​​expressed in IP units (inch-pound) are about 5.68 times greater than when expressed in SI units, so that, for example, the R-2 window in the IP unit has a RSI of 0.35 (since 2/5.68 = 0.35). For R-values, there is no difference between US customary units and imperial units. To what extent is the R-value reported, all of the following mean the same thing: - this is the R-2 window ?; ? this is R2 window ?; ? this window has R2 value; ? This is a window with R = 2? (and also with RSI-value, which also includes the possibility of? this window gives RSI 0.35 resistance to heat flow?).

The more the material is intrinsically capable of heat, as provided by the thermal conductivity, the lower the R value. On the other hand, the thicker the material, the higher the R value. Sometimes other heat transfer processes than conduction (ie convection and radiation) significantly contribute to heat transfer within the material. In such cases, it is useful to introduce 'clear thermal conductivity', which captures the effects of all three types of processes, and to define the R-values ​​in general as ${\ displaystyle R = {\ frac {\ scriptstyle {\ text {specimen thickness}}} {\ scriptstyle {\ text {thermal conductivity clear}}} }}$ . This comes at a price, however: R-values ​​that include non-conductive processes may no longer be additive and may have significant temperature dependence. Specifically, for loose or porous materials, the R value per inch is generally dependent on the thickness, almost always decreasing with increasing thickness (polyisocyanurate (? Polyso?) Being an exception; the R/inc value increases with thickness). For the same reason, the R value per inch also depends on the temperature of the material, usually increasing with a decrease in temperature (polyso again being an exception); a R-13 fiberglass batt may be nominal R-14 at -12 ° C (10 ° F) and R-12 at 43 ° C (110 ° F). However, it is in general construction to treat the R-value as independent of temperature. Note that the R-value may not take into account the radiation or convective processes on the surface of the material , which may be an important factor for some applications.

The R value is the inverse of the thermal (U-factor) transmittance of the material or assembly. The US construction industry prefers to use the R-values, but because they are additive and because of greater value means better isolation, there is nothing right for the U-factor.

Video R-value (insulation)

U -faktor/nilai-U

The U-factor or U-value is the overall heat transfer coefficient describing how well the building element performs heat or the heat transfer rate (in watts) through one square meter of structure divided by temperature differences across structures. The elements are generally a collection of many layers of components such as making walls/floors/roofs etc. It measures the rate of heat transfer through building elements above a certain area under standard conditions. The usual standard is at a temperature gradient of 24 ° C (75.2 ° F), at 50% moisture with no wind (the lower U-factor is better at reducing heat transfer). Expressed in watt per meter of squares kelvin (W/mÃ,²K). This means that the higher the U value, the worse the thermal performance of the building envelope. A low U value usually indicates a high degree of insulation. They are useful because they are a way of predicting the combined behavior of all building elements rather than depending on individual material properties.

In most countries the properties of certain materials (such as insulation) are indicated by thermal conductivity, sometimes called k-values ​​or lambda values ​​(lowercase?). Thermal conductivity (k-value) is the ability of a material to heat; hence, the lower the value of k, the better the material for insulation. Expanded polystyrene (EPS) has a k value of about 0.033 W/mK. By comparison, the fenolic foam insulation has a k value of about 0.018 W/mK, whereas the wood varies from 0.15 to 0.75 W/mK, and the steel has a k value of about 50.0 W/mK. These figures vary from product to product, so the UK and EU have set the 90/90 standard which means that 90% of the products will correspond to the k-value declared with 90% confidence level as long as the quoted figure is expressed as 90/90 lambda -value.

U adalah kebalikan dari R dengan satuan SI dari W/(m ² K) dan unit AS BTU/(hr  ° F ft) ² );

${\ displaystyle U = {\ frac {1} {R}} = {\ frac {{\ dot {Q}} _ {A}} {\ Delta T}} = {\ frac {k} {L}}}  ÂÂ$

di mana ${\ displaystyle {\ dot {Q}} _ {A}}  ÂÂ$ adalah fluks panas, ${\ displaystyle \ Delta T}  ÂÂ$ adalah perbedaan suhu di seluruh material, k adalah koefisien konduktivitas panas material dan L adalah ketebalan. Dalam beberapa konteks, U disebut sebagai konduktansi permukaan unit.

See also: tog (unit) or Thermal Overall Grade (where 1g = 0.1 m ² Ã, Â · K/W), used for rating quilts.

Note that the term "U-Factor" (which is routed here) is usually used in the US and Canada to express the heat flow through the entire assembly (such as roofs, walls, and windows). For example, energy codes such as ASHRAE 90.1 and IECC prescribe U-values. However, R-values ​​are widely used in practice to describe the thermal resistance of insulation products, layers, and most other parts of the building enclosure (walls, floors, roofs). Other regions of the world more commonly use U/U-factor values ​​for the overall elements of the building including windows, doors, walls, roofs, and slabs.

Maps R-value (insulation)

Units: metric (SI) vs pound-inch (IP)

SI unit (metric) of R-value is

kelvin square meter per watt (m ² Ã, Â · K/W or, equals, m ² Ã, Â · Â ° C/W ),

while the I-P (Inci-pound) unit is

square-footÃ, Â · degrees FahrenheitÃ, clock/British thermal unit (ft ² Ã, Â · FÂ ° Â · h/BTU).

For R-values ​​there is no difference between US customary units and imperial units, so the same I-P units are used in both.

Some sources use? RSI? when referring to the R-value in SI units.

The R-value expressed in units of I-P is about 5.68 times greater than the R-value expressed in SI units. For example, the R-2 window in the I-P system is about RSI 0.35, since 2/5.68? 0,35.

In countries where SI systems are generally used, R-values ​​are also usually given in SI units. These include the United States, Australia, and New Zealand.

I-P values ​​are usually awarded in the U.S. and Canada, although in Canada typically the I-P and RSI values ​​are listed.

Since the units are not usually explicitly stated, one must decide from the context of which unit to use. In this case, it is important to remember that the R-P value is 5.68 times greater than the corresponding R R value.

More precisely, R-value (in I-P) = RSI value (in SI) ÃÆ'â € "5.678263337

RSI value (in SI) = R-value (in I-P) ÃÆ'â € "0,1761101838

src: www.vendermicasa.org

Different insulation type

The Australian Government explains that the total R value required for building fabrics varies depending on the climate zone. "Such materials include aerated concrete blocks, expanded polystyrene blocks, straw bales, and extruded polystyrene sheets."

In Germany, after the Energieeinsparverordnung (EnEv) legislation introduced in 2009 (October 10) on energy savings, all new buildings must demonstrate the ability to remain within certain limits of the U-value for each particular building material. Furthermore, EnEv describes the maximum coefficient for each new material if replacement parts are replaced or added to the standing structure.

The US Department of Energy has recommended R-values ​​for certain areas of the United States based on common local energy costs for heating and cooling, as well as the climate of an area. There are four types of insulation: scroll and batt, loose-fill, rigid foam, and foam in place. Rolls and batts are usually flexible insulators that come in fibers, such as fiberglass. Loose-fill insulation is equipped with loose fibers or pellets and must be blown into the chamber. Rigid foams are more expensive than fiber, but generally have a higher R value per unit of thickness. Foam insulation in place can be blown into a small area to control air leaks, such as around a window, or can be used to protect the entire house.

src: www.ncptt.nps.gov

Thickness

Increasing the thickness of the insulating layer improves heat resistance. For example, doubling fiberglass batting thickness will double the R value, possibly from 2.0 m ² K/W for a thickness of 110 mm, up to 4.0 m ² K/W for 220 mm thickness. The heat transfer through the analog isolation layer by adding resistance to the series circuit with a fixed voltage. However, this only holds around because of the effective thermal conductivity of some insulating materials depending on the thickness. The addition of materials to attach insulation such as sheetrock and coatings gives an additional R value but is usually much smaller.

src: www.greenbuildingadvisor.com

Factor

There are many factors that come into play when using R-values ​​to calculate the heat loss for a particular wall. The R-value manufacturer only applies to properly installed insulation. Squeezing two layers of batting into a thickness intended for one layer will increase but not doubling the value of R. (In other words, compressing fiberglass batts reduces the R value of the batt but increases the R value per inch.) Another important factor to consider is that the stud and the window provides a parallel hot conduction path not affected by the R-value isolation. The practical implication of this is that one can multiply the R value of insulation installed among framing members and realize substantially less than 50 percent reduction in heat loss. When mounted between wall studs, even perfect wall insulation only removes conduction through insulation but leaves are not affected by conductive heat lost through materials such as window glasses and buttons. Insulation installed between the buttons can reduce, but usually does not eliminate, heat loss due to air leakage through the building envelope. Installing a continuous rigid foam insulation layer on the outer side of the sheathing wall will disrupt the thermal connecting through the button while also reducing the rate of air leakage.

src: horssols.com

Primary role

The R value is a measure of the ability of the isolation sample to reduce the heat flow rate under specified test conditions. The main mode of heat transfer inhibited by insulation is conduction, but insulation also reduces heat loss by all three heat transfer modes: conduction, convection, and radiation. The loss of primary heat in air-filled empty spaces is natural convection, which occurs due to changes in air density with temperature. The deeply inhibiting isolation of natural convection makes the main mode conduction of heat transfer. The porous isolation achieves this by trapping air so that significant convective heat loss is eliminated, leaving only conduction and small radiation transfer. The main role of such insulation is to make the thermal conductivity of the trapped insulation, the air being stagnant. However this can not be realized completely because the glass or foam wool needed to prevent convection increases heat conduction compared to the still air. Minor radiative heat transfer is obtained with many interfering surfaces of "clear view" between the inner and outer surfaces of the insulation as visible light is disturbed as it passes through the porous material. Such multiple surfaces abound in batting and porous foam. Radiation is also minimized by low emissivity (highly reflective) external surfaces such as aluminum foil. Lower thermal conductivity, or higher R values, can be achieved by replacing air with argon when practicable as in special pore-covered foam insulation because argon has a lower thermal conductivity than air.

src: www.greenintegrateddesign.com

General

The heat transfer through the insulating layer is analogous to the electrical resistance. The heat transfer can be worked out by thinking of the resistance in series with a fixed potential, unless the resistivity is thermal resistance and the potential is the temperature difference from one side of the material to the other. The resistance of each material to heat transfer depends on the specific thermal resistance [R-value]/[unit of thickness], which is the material property (see table below) and the thickness of the layer. A thermal barrier consisting of multiple layers will have several thermal resistor in analog with the circuit, each series.

Like resistance in electrical circuits, increasing the physical length of resistive elements, such as graphite for example, increases the resistance linearly; doubling the coating thickness means doubling the R value and half the heat transfer; quadruple, quarters; etc. In practice, this linear relationship does not apply to compressible materials such as glass, wool, and cotton whose thermal properties change when compressed.

src: horssols.com

Calculates heat loss

To find the average heat loss per unit area, simply divide the temperature difference by the R-value for the layer.

If the interior of the house is at 20 Ã, Â ° C and the roof cavity is at 10 Ã, Â ° C then the temperature difference is 10 Ã, Â ° C (or 10Ã, K). Assuming the ceiling is insulated for RSI 2.0 (R = 2 m ² K/W), the energy will disappear at the rate of 10 KK/(2 K 2 /W ) = 5 watts per square meter of ceiling. The RSI value used here is for the actual insulation layer (and not per insulation thickness unit).

src: horssols.com

Relationships

Thickness

The R-value must not be confused with the intrinsic properties of thermal resistivity and its inverse, thermal conductivity. The SI unit of thermal resistivity is K Â · m/W. Thermal conductivity assumes that the material heat transfer is linearly related to its thickness.

Many layers

In calculating the R value of a multi-layered installation, the R-values ​​of each layer are added:

R-value _{(outer air film)} R-value _(brick) R-value _(coating) R-value _(insulation) R-value _{(in the air film)} = R-value _(total) .

To calculate other components in the wall such as framing, first calculate the U-value (= 1/R-value) of each component, then the weighted average U-point of the region. The average R value will be 1/(this average U value). For example, if 10% of the area is 4 inches of softwood (R-value 5.6) and 90% is 2 inches of aerogic silica (R-value 20), the U-area-weighted value is 0.1/5.6 0.9/20 = 0 , 0629 and the weighted R value is 1/0,0629 = 15,9.

src: www.greenintegrateddesign.com

Controversy

Thermal conductivity to clear thermal conductivity

Thermal conductivity is conventionally defined as the thermal conduction rate through material per unit area per unit of thickness per unit of differential temperature (? T). Inverter conductivity is resistivity (or R per unit thick). Thermal conductance is the rate of heat flux through the unit area at the installed and given thickness?

Experimentalally, thermal conduction is measured by placing the material in contact between two conducting plates and measuring the energy flux required to maintain a certain temperature gradient.

For the most part, R-value insulation testing is performed at a stable temperature, typically around 70Ã, Â ° F (21Ã, Â ° C) without any surrounding air movement. Since this is an ideal condition, the listed R values ​​for isolation will almost certainly be higher than would be actually used, as most situations with isolation are in different conditions.

The definition of R-value based on thermal conductivity has clearly been proposed in document C168 published by the American Society for Testing and Materials. It describes the heat transferred by the three mechanisms - conduction, radiation, and convection.

Debates persist among representatives of different segments of the US insulation industry during the revision of the US FTC rules on R-value advertising that illustrates the complexity of the problem.

Surface temperature in relation to heat transfer mode

There is a disadvantage to using a single laboratory model to simultaneously assess the material properties to withstand heating, radiation, and convection. The surface temperature varies depending on the heat transfer mode.

In the absence of radiation or convection, the surface temperature of the insulator should be equal to the air temperature on each side.

In response to heat radiation, the surface temperature depends on the thermal emissivity of the material. The surface of light, reflective, or radiated metal tends to maintain a lower temperature than the dark and non-metallic.

Convection will change the rate of heat transfer (and surface temperature) of the insulator, depending on the characteristics of the flow of gas or liquid contacting it.

With some heat transfer mode, the final surface temperature (and hence the observed energy flux and calculated R value) will depend on the relative contribution of radiation, conduction, and convection, although the total energy contribution remains the same.

This is an important consideration in building construction because the heat energy arrives in different forms and proportions. The contribution of radiation and conductive heat sources also varies throughout the year and both are important contributors to thermal comfort

In summer, solar radiation predominates as a source of heat gain. According to Stefan-Boltzmann's law, radiant heat transfer is related to the fourth power of absolute temperature (measured in kelvin: T [K] = T [Â ° C] 273.16). Therefore, such transfer is the most significant when the goal is to cool (ie when solar radiation has produced a very warm surface). On the other hand, conductive and convective heat loss modes play a more significant role during the cold months. At lower ambient temperatures, fibrous insulation, plastics and traditional cellulose play a major role: radiation heat transfer components are much less important, and the main contribution of radiation barriers in superior air-chafing contributions. In summary: claims for the isolation of a luminous barrier can be justified at high temperatures, usually when minimizing summer heat transfer; but this claim can not be justified in traditional winter conditions (keeping warm).

Limitations of R-values ​​in evaluating radiation resistance

Unlike bulk insulators, the radiation barrier retains poor heat. Materials such as reflective foil have high thermal conductivity and will function poorly as conductive insulators. The radiation resistance inhibits heat transfer in two ways: by reflecting radiation energy from its surface and by reducing emission of radiation from the opposite side.

Questions about how to measure the performance of other systems such as radiation barriers have resulted in controversy and confusion in the building industry with the use of R-values ​​or 'equivalent R values' for products that have very different thermal transfer inhibitory systems. (In the US, the federal Rule Value R specifies the legal definition for the R-value of building materials, the term 'equivalent-R value' has no legal definition and therefore does not mean.) According to the current standard, the most reliable R-values for bulk insulation materials. All products quoted at the end are examples of this.

Calculate the performance of more complex radiation resistance. With a good luminous barrier in place, most of the heat flow is through convection, which depends on many factors other than the radiation barrier itself. Although the radiation barriers have high reflectivity (and low emissivity) above the range of the electromagnetic spectrum (including visible light and UV light), their thermal superiority is mainly related to their emissivity in the infra-red range. Emissivity value is the right metric for the radiation barrier. Their effectiveness when used to withstand heat gain in a limited application is fixed, even though the R-value does not adequately describe it.

src: horssols.com

Deterioration

Insulation aging

The values ​​of product R may deteriorate over time. For example the loose filler cellulose compaction creates a cavity that reduces overall performance; this can be avoided by packing the initial installation with solid. Some types of foam insulation, such as polyurethanes and polyisocyanurates, are exhaled with heavy gases such as chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HFCs). However, over time a small amount of these gases diffuses out of the foam and is replaced by air, thereby reducing the effective R value of the product. There are other foams that do not change significantly with aging because they are blown with water or open cells and do not contain trapped CFC or HFC (for example, half-pound density foam). In certain brands, a twenty year test shows no depreciation or reduction in the value of isolation.

This has caused controversy as a way of assessing the insulation of these products. Many manufacturers will assign an R-value at the time of manufacture; critics argue that a fairer judgment will be a settled value. The foam industry adopts the LTTR (Long Term Term Thermal Resistance) method, which assesses the value of R based on the 15-year weighted average. However, LTTR effectively only gives R values ​​that are eight years old, short on a building scale that may have a lifespan of 50 to 100 years.

Infiltration

Proper attention to air sealing measures and the consideration of vapor transfer mechanisms are important for optimal functioning of bulk insulators. Water infiltration may allow convective heat transfer or condensation formation, both of which can decrease insulation performance.

One of the key values ​​of spray foam insulation is its ability to create airtight seals (and in some cases, impermeable) directly to the substrate to reduce unwanted leakage effects.

src: images.homedepot-static.com

In-situ measurements R-value

Damage to R values ​​is primarily a problem when defining energy efficiency of existing buildings. Especially in old or historic buildings, the R-values ​​defined before construction may be very different from their true values. This greatly affects energy efficiency analysis. To obtain reliable data, the R-value is therefore often determined by the measurement of U-values ​​at a particular location (in situ). There are several potential methods for this, each with their specific trade-offs: thermography, double temperature measurement, and heat flux method.

Thermography

Thermography is applied in the building sector to assess the thermal insulation quality of the room or building. By using thermal camera thermal bridges and non-homogeneous insulation parts can be identified. However, it does not produce quantitative data. This method can only be used to estimate a U-value or an inverted R value.

Multiple temperature measurements

This approach is based on three or more temperature measurements inside and outside the building element. By synchronizing these measurements and making some basic assumptions, it is possible to calculate the heat flux indirectly, and thus decrease the U value of the building element. The following requirements must be met for reliable results:

• The difference between inside and outside temperatures, ideal & gt; 15 K
• Constant condition
• No solar radiation
• There is no radiation heat measurement around

Heat flux method

U values ​​can be calculated also by using heat flux sensors in combination with two temperature sensors. By measuring the heat flowing through the building element and combining this with the temperature inside and out, it is possible to determine the exact U-value. Measurements that last at least 72 hours with a minimum temperature difference of 5 Â ° C are required for reliable results in accordance with ISO 9869 norms, but shorter measurement durations provide reliable indication of U-value as well. The progress of measurement can be seen on the laptop through the appropriate software and the data obtained can be used for further calculations. Measurements for such hot flux measurements are offered by companies such as FluxTeq, Ahlborn, greenTEG, and Hukseflux.

src: www.rhinobldg.com

Example value

The vacuum insulated panel has the highest R value, about R-45 (in US units) per inch; Aerog has the next highest R value (about R-10 to R-30 per inch), followed by polyurethane (PUR) and phenolic foam insulation with R-7 per inch. They were followed by polyisocyanurate (PIR) in R-5.8, expanded polystyrene graphite impregnated in R-5, and expanded polystyrene (EPS) at R-4 per inch. Loose cellulose, fiberglass (both blown and in batt), and rock wool (both blown and in batt) all have R values ​​ranging from R-2.5 to R-4 per inch.

Roll straw performs about R-1.5 per inch. However, typical straw bales houses have very thick walls and thus are well insulated. Snow is roughly R-1 per inch. Bricks have very poor insulation capability of only R-0.2 per inch; But it has a relatively good thermal mass.

Note that the examples above all use the US definition (non-SI) for the R-value.

Standard R values ​​(per inch of material)

Standard R-values ​​for surface

R values ​​of non-reflective surfaces for aerial film

When determining the overall thermal endurance of building assemblies such as walls or roofs, the insulating effects of surface air films are added to the thermal endurance of other materials.

In practice, the above surface values ​​are used for floors, ceilings, and inner walls of buildings, but are not accurate for closed air cavities, such as between glass. The effective thermal resistance of the closed air cavity is strongly influenced by radiant heat transfer and the distance between the two surfaces. See insulated glazing for R-value comparisons for windows, with some effective R values ​​that include air cavities.

Radiation barriers

R-Value rule in the US.

The Federal Trade Commission (FTC) regulates claims of R-value to protect consumers from misleading and misleading advertising claims. "The Commission issued the R-Value Rule

The main purpose of this rule is to ensure that the home insulation market provides this important pre-purchase information to consumers. This information gives consumers the opportunity to compare the relative isolation efficiency, to select the product with the greatest efficiency and energy savings potential, to make cost-effective purchases and to consider the main variables that limit the effectiveness of isolation and the realization of the claimed energy savings.

Rules mandate that specific R-value information for home insulation products is disclosed in certain advertisements and at point of sale. The purpose of the R-value disclosure requirements for advertising is to prevent consumers being misled by certain claims that have an influence on the value of isolation. At the transaction point, some consumers will be able to obtain the required R-value information from the label on the isolation package. However, since the evidence suggests that packages are often unavailable for review before purchase, there is no labeled information that will be available to consumers in many instances. As a result, the Regulations require fact sheets to be available for consumers to review before they make a purchase.

Thickness

The R-value rule specifies:

src: images.homedepot-static.com

See also

• Building insulation
• Building insulation materials
• Condensation
• Cool roof
• Hot transfer
• Passivhaus
• Passive solar design
• Hot air temperature
• Superinsulation
• Thermal bridge
• Thermal comfort
• Thermal conductivity
• Thermal mass
• Thermal transmission
• Tog (unit)

src: www.eco-panels.com

References

src: images.homedepot-static.com

External links

• The Insulation Value R-Value table at InspectApedia includes original
source citations
• Information on calculations, meanings, and interrelationships of related heat transfer and resistance terms
• Table R-value of American building materials
• Works with R-values ​​

Source of the article : Wikipedia