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Frequently Asked Questions

General Product Questions

What are the key differences between the Wired and Wireless system?

  • UVAL Wireless supports up to 5 measurement points per system, offering greater flexibility in data collection. UVAL Wired only supports one U-value measurement.

  • UVAL Wireless allows for remote monitoring. This enhances convenience and efficiency. Our Wired system requires direct access to the site to receive data recordings.
  • UVAL Wireless provides direct measurements for U-Value, R-Value, and Lambda Value. UVAL Wired provides only U-Value measurements; you would need to calculate the R-Value separately.
  • UVAL Wireless is an expandable system, meaning you can purchase more measurement points over time. UVAL Wired is not expandable.

 

Do I need remote access to use the UVAL Wireless System?

  • No. The system works locally.

  • The Remote Measurement Access add-on is only for remote viewing/management (1-year free trial, then CHF 199/year).

  • For UVAL Wired, no remote access is available.

 

What countries are the systems available in?

  • Customers worldwide can purchase and use our UVAL Wired System.

  • UVAL Wireless is only available in Europe, most of Africa, and the Middle East. This is because it employs a sub-GHz Communication link at 868 MHz.*
*If you are interested in our UVAL Wireless system and you are located outside of Europe, please reach out to us and we can evaluate a customized option.

 

What is the operating principle of the UVAL Wireless System?

The nodes communicate to the base station, which stores all the data. Nodes only transmit data when someone plugs a sensor into them. When you’re not taking measurements, please disconnect the sensors.

The nodes communicate to the base station on a specific subGHz frequency. 
Can I unplug my UVAL Wireless base station?

Connect the base station to a power source during measurement, as its battery life is 48 hours. ISO 9869 compliancy requires a minimum measurement period of 72 hours.

 

What are the warranty terms?

  • 12-month limited warranty for materials/workmanship when used correctly.

  • Please report any defects within 14 days of discovery.

 

Is the software included?

  • Yes, the software is included in your purchase.

  • For remote access via the cloud, the software is available through a 1 year trial, and afterwards costs CHF 199 per year.

 

What happens when the node battery dies?

Node batteries last 2 years. The batteries can be replaced easily on the market for less than 10 CHF. We are also happy to replace these if preferred.

 

Measurement Method & Accuracy

Which standard does UVAL follow?

ISO 9869-1 (heat-flow meter method) for in-situ thermal resistance/transmittance.

 

How long should I measure U-value for?

Plan for ≥72–96 hours with ΔT ≥ 5 °C between inside and outside. The longer the better if ΔT is small or the environment is unstable.

 

Do you account for dynamic or storage effects?

Indirectly, ISO 9869 uses multi-day windows (multiples of 24 h) and stability checks (compare first vs. last 24 h), so transient effects average out.

 

How do you compute U-Value and R-Value?

  • U-value: (U = q / \Delta T) (W·m⁻²·K⁻¹)

  • R-value: (R = 1/U) (m²·K·W⁻¹)
What temperature conditions should be considered?

There should be a minimum difference of 5°C between exterior and interior environments. This requirement can make conducting summer measurements more challenging.

 

What standards must I comply with for an accurate measurement?

Data collection, analysis, and reporting per ISO 9869-1 (heat-flow meter method).

 

Sensor Mounting & Environment

Can I measure a wall near a window?

  • Yes. Make sure to keep ≥ 3× wall thickness from the window edge to avoid any potential edge effects (e.g., 30 cm wall → ≥ 90 cm away).

  • Place the outside temperature probe so it reflects the cavity air, often close to the ambient sensor. Positioning this on the outermost layer is fine.

 

How do humidity and condensation affect U-value?

U-value is defined for dry heat transfer. It is best to avoid evaporation/condensation. Ensure the air dew point is below the coldest air temperature in your setup.

 

Do you have any recommendations for sun, rain, or snow?

  • Often, north-facing surfaces are preferred in order to reduce solar effects. It is a good idea to avoid direct sunlight for U-value measurements.

  • In rain or snow conditions, place each node in a vented plastic bag (e.g., Ziploc) so cables exit and protect electronics while allowing ventilation.

 

Which building envelopes are most commonly measured on?

  • Our U-Value measurement systems can record measurements on most building envelopes.

  • Vented cavities do not support accurate in-situ U-Value measurements.

 

What conditions should I be wary of?

Outside:

  • Avoid direct sunlight

  • Protect from large rainfall.

  • greenteg’s node and outdoor sensors are rated IP67.

Inside:
  • Ensure the room is not occupied.
  • Avoid heaters, drafts, and mold presence.

 

Tape vs. Thermal putty: Which do you recommend?

  • Use double-sided tape whenever possible.

  • Use putty only on very rough/uneven surfaces where tape can’t achieve contact.

  • It is recommended not to combine tape + putty on smooth surfaces.

 

How many sensors and readings do I get for the UVAL Wireless Kit?

  • Both the inside and outside sets receive one node, and two sensors.

  • The inside set receives 3 readings (heat flux, surface temperature and ambient temperature).

  • The outside set receives 2 readings (surface temperature and ambient temperature).

 

Special U-Value Applications

Can I measure thermal bridges (e.g., concrete lintels)?

You can, but please interpret with care:

  • Sensor active area: 10×10 mm; overall footprint: 30×30 mm.
  • Keep ≥ 3× wall thickness from edges/heterogeneities.
  • Small or narrow bridges distort local heat flow. It is worth considering multiple points and/or overlay.

 

Can I measure the U-value of glass?

Yes, with proper ΔT and stable boundary conditions.

 

Is a vented cavity suitable for U-value?

Not for true U-value of the element alone as the airflow complicates heat transfer. It is recommended to use inner-side measurements and document boundary conditions if unavoidable.

 

Can I measure U-Value on a window?
  • Yes, it is possible to measure U-Value on a window. It is important to note that window measurements should only utilize nighttime data.
  • Window measurements are not ISO compliant. Only nighttime readings are accurate, therefore you would not fulfil the 72-hour consecutive measurement period.
What exterior building conditions should I watch out for?

Direct sunlight should be avoided on the sensors. greenteg’s node and outdoor sensors are rated IP67.

What's the minimum period for an ISO calculation?

72 hours is the minimum ISO 9869 measurement requirement, however ideally you need at least 96 hours.

Do you support acoustic/noise transmission measurements?

No. Both UVAL Wired and UVAL Wireless support thermal measurements only. All other UVAL-related sensors also support thermal measurements only.

 

Have more questions?

Didn't find the answers you were looking for? Reach out to us through our contact us page with your questions, and a member of our team will get back to you as soon as possible.