We received many inquiries on UVC measurement instruments for medical equipment disinfection applications.
The UVC-CK01 kit is a complete UVC irradiance measurement kit by Delta Ohm. It is a plug-and-play system with user-friendly operations. It is also with data logging function for continuous recording of historical data. Read the news at Delta Ohm website for more details.
Our newsletter OTM Insights Issue 4 was sent to our customer on 27 Apr 2020. We are sharing some technical insights of optical & thermal property test of glasses from existing buildings in the newsletter. Click the image to read the full newsletter.
Our newsletter OTM Insights Issue 3 was sent to our customer on 03 Feb 2020. We are sharing some technical insights of partially fritted glazing optical & thermal property testing procedures in the newsletter. Click the image below to read the full newsletter.
Color and gloss are commonly used quality check quantities by material suppliers and construction companies, whereas daylight reflectance are relatively new to the industry. This article aims to explain the relationship between the three quantities.
Daylight reflectance and color
The total and diffuse daylight reflectance is directly related to color. Materials with light color are with high total or diffuse daylight reflectance; materials with dark color are with low total or diffuse daylight reflectance. Our eyes cannot quantify daylight reflectance, but they can assess daylight reflectance qualitatively.
Most color instruments with integrating sphere geometry can measure color in the SCI (specular component included) mode or the SCE (specular component excluded) mode. Color measured in the SCI mode is equivalent to the total daylight reflectance; color measured in the SCE mode is equivalent to the diffuse daylight reflectance.
The closest color scale is Yxy scale. Of course, due to various technical constraints, color measurement instruments cannot accurately determine daylight reflectance, but the results are sufficient for internal use.
Daylight reflectance and gloss
The specular daylight reflectance is directly related to gloss. Materials with high gloss are with high specular daylight reflectance; materials with low gloss are with low specular daylight reflectance. Our eye can qualitatively assess if a surface is with high gloss or with low gloss.
Gloss meters can measure material gloss level. However, the relationship between gloss meter readings and specular daylight reflectance is qualitative. It is not possible to quantitatively coorelate them.
Notes to applications
For projects where low specular daylight reflectance is required, materials with low gloss level are preferred.
For projects where low total daylight reflectance is required, materials with dark color are preferred.
Some example calculations were conducted to illustrate the possible differences between EN, ISO and NFRC glazing system test methods. The three standards are widely used, but specific national standards may exist for respective countries (e.g. JIS R3106:1998 and JIS R3107:1998 for Japan).
There are relatively large discrepancies among the solar related quantities (ST, SR, G and SC) calculated by the three methods, particularly for the double glazing unit with high spectral selectivity
The reference solar spectrum in EN 410 is based on the AM1 global spectrum (direct + diffuse) defined in CIE 085:1989
ISO 9050 uses AM1.5 global spectrum (direct + diffuse) defined in ISO 9845-1:1992
NFRC 300 uses AM1.5 direct normal spectrum defined in ISO 9845-1:1992
There are some discrepancies among the thermal transmittance quantities (U) calculated by the three methods, particularly for the single glazing system with hard low-e coating on surface #2 (summer condition U-value is significantly lower)
The internal and external surface heat transfer coefficients defined in the three methods are different
There is no separate summer condition thermal transmittance in the EN and ISO methods
Which test method shall I use?
All methods are widely accepted and fair comparison can be made only if the results are from the same method
It is not appropriate to compare results obtained with different methods
It is at the end user’s discretion on method selection. Your end user could be internal staffs, project owners, certification bodies or government agencies.
If the end user has no preference, NFRC method is recommended due to the availability of a suite of software tools. The summer condition thermal transmittance is also more relevant for summer condition applications