How to measure U-value

# How can I obtain the U-value of my Building?

Stakeholders in the building industry often face the problem of obtaining a reliable U-value for Walls, Roofs, and Windows. This is due to the U-values that are on record for these materials being old and unreliable.

## How can the the U-value of a building element be measured?

greenTEG has two data-driven Building Envelope Measurement Systems featuring our patented gSKIN® heat flux sensing technology. The suitable system for your project depends on the scale of your project, the values that need to be obtained, and whether you require a wireless solution.

Want to understand more about greenTEG’s U-Value measurement solutions? Explore more about our products and their features by clicking on the image to the right!

### Temperature Based Method vs. Heat Flux Based Method

In a study performed by students at East Bavarian Technical University, the measurement quality of U-values measured with a Temperature Based Method (TBM) versus a Heat Flux Based Method (HFBM) were compared. It was found that the HFBM U-value measurement not only stabilised more quickly, but was also more accurate.

By measuring the U-value of a refrigerator’s insulation wall, it was found that TBM-derived U-value varied with day and night temperature cycles across 41 hours, while the U-value obtained with the U-value Kit stabilised after 12 hours. The report explains the underlying reason for the difference between the two results: A constant convective transfer coefficient is assumed for the TBM, while this coefficient is measured in the HFBM. The full study is available here entitled “Heat transfer coefficient of a building element. Methods comparison”.

## How can I measure the U-value of a Window?

U-value measurements of windows are necessary to quantify the performance and the energy saving potential of built-in windows. Good insulation properties of the window pane reduce energy loss in cold climates and energy input in hot climates respectively.
However, solar radiation on the window distorts the heat flux measurements. Therefore, U-values on windows are harder to measure than on walls.

In this case study, we used the example of a house from the 1930s to show how you can measure U-values of windows easily and precisely, in little time, all year round with the gO Measurement System from greenTEG. The full case study is available here.

## How can I measure the U-value of a Roof?

This brief case study presents the challenges of performing a U-value measurement on a roof and the precautions and steps to overcome them. The challenges of measuring a very low U-value and the corresponding measurement quality assessment methods are also discussed. A potential solution, in the form of a U-value calculation algorithm, is then proposed to faster achieve ISO 9869 conformity. The full description is available on this dedicated page.

How to measure the U-Value of a Roof

## Facing unique conditions for your U-value measurement?

Your measurement conditions may never be perfect. Our guide will give advice for your project’s unique set of circumstances.

## How can I measure the U-values of an entire home?

John Gilbert Architects used the gO-Measurement System to perform U-value measurements on two Scottish public housing sites.

Using the measurement data, John Gilberts Architects prepared evidence-based, best case retrofit guidance for the public housing authorities.

This optimizes the return on property investment, while maximizing energy efficiency gains. In a few months from now, the post-retrofit U-values are planned to be measured to verify that the construction work has achieved its design targets. The full case study is available here.

## How can I measure the U-value for Building Standard Certification?

### MINERGIE certification for the building

In our latest case study, we show you how a U-value measurement will tell you whether the contractor botched up the insulation job! 🔍

The owners of a newly built single-family home wanted to get the MINERGIE certification for the building. Discover what happened in the full case study available here in English and Deutsch.

### The Swiss room climate standard certification (SIA 180)

The Swiss standard SIA 180 includes requirements for heat protection, damp-proofing and indoor climate in buildings. Amongst other necessities, it requires the use of a floor whose thermal storage capacity can be used. In a pilot project, building scientists were uncertain whether the application of an insulating flooring (for example, parquet, linoleum, etc.) would fail in complying with the limit values per SIA 180. Our U-Value Kit allows to simply and precisely check these conditions.

Measurements have shown that a flooring such as novilon / linoleum has no or only insignificant influence on the thermal performance of the floor (see diagram). In a test, the heat flux sensors of two U-Value Kits were positioned at two different locations on the floor of a building. Once on bare artificial stone flooring and once on novilon / linoleum, which was mounted on the artificial stone flooring.