The Thermosash curtainwall U-value calculator is a free, online tool designed to guide specifiers and construction stakeholders to estimate U-values for potential configurations of their individual projects using the Thermosash range of Panel wall (unitised) façade systems.
Calculating U-values for façade panels has many influential factors, including; Thermal frame type, width and height of the panel, location of the spandrel as well as the insulation thickness, and then the glass types. There are potentially limitless configurations. This calculator can be used to provide indicative performance values for various panel configurations and framing selections however, we recommend with all projects that you contact us to discuss your project in detail to provide further guidance on material selection, thermal performance, embodied carbon and to tailor a solution to meet your specific needs.
What is U-value?
The calculator returns an area weighted U-value being an average of the amount of heat transfer expected across the panel per square meter per degree differential between inside and outside. The U-value describes how effective the assembly is of insulating warm from cold.
Some building products express this as an R-value which is the inverse of the U-value.
U (W/m2K) = 1/R(m2K/W)
Caution should be taken with relying too heavily on U-value only to assess material selection for you projects. Many factors can influence human comfort and annual building energy performance including U-value, Solar Heat Gain Coefficient, air permeability and radiance/glare.
Our free calculator uses a database of Thermosash curtainwall framing cross-sections, IGU build-ups and insulation depths that have been thermally modelled in Flixo to ISO 10077-2:2017 and ISO 12631: 2017. We appreciate that the calculator may not fully represent panels from your proposed facade shape or might not provide a figure you require.
We recommend with all projects that you contact us to discuss your project in detail to provide further guidance on material selection, thermal performance, embodied carbon and to tailor a solution to meet your specific needs.
To use the calculator simply enter or select values from the fields below following any on screen tips.
Calculation Results
A U-Value, also known as thermal transmittance, is the rate of heat transfer through a structure divided by the heat differential across that structure. Thermal performance is commonly expressed in the construction industry as a U-Value or R-Value. The U-Value of a structure is measured in Watts per meter squared multiplied by the temperature difference or W/m2K. As the thermal performance of the structure improves, the U-Value decreases.
The R-Value is the reciprocal of the U-Value. Due to it being the reciprocal of the U-Value, as thermal performance improves, the R-Value of the structure increases as well.
Clause H1 of the New Zealand Building sets the minimum energy performance targets for New Zealand buildings. New Zealand has been divided into 6 climate zones based on temperature and weather patterns. Like most building codes, compliance can be demonstrated by Acceptable Solutions where minimum construction R-values for various elements of the building has been specified in each zone. Curtainwall Facades have been excluded from the acceptable solutions methods and compliance must be demonstrated via a Verification Method which assesses the proposed buildings construction against a reference building at the same proposed location and orientation.
Some housing assessment have attributed as much as 50% of the annual energy loss through the building envelope to windows. For this reason, it is important to select energy efficient windows with low U-values. It is important however to also assess the airtightness, and solar heat gain on the annual building energy requirements to ensure windows are selected to provide the best total performance for your budget and deign aesthetic.
A thermally broken window features a separation of the outside framing and materials, from the inside framing and materials with a low thermally-conductive piece of material or by machining that removes the connection from outside to inside. This interrupts the heat transfer pathway and makes it much more difficult for heat to transfer between the interior and exterior of a building through the framing elements.
