Grantee Research Project Results

Final Report: Highly Insulating Glazing Systems Using Liquid Fills

EPA Grant Number: SU835504
Title: Highly Insulating Glazing Systems Using Liquid Fills
Investigators: Sylvester, Keith , Adu, Bright , Moses, Mychal-Drew , Shephard, Terone
Institution: Western Kentucky University , Bowling Green State University - Main Campus
EPA Project Officer: Packard, Benjamin H
Phase: I
Project Period: August 15, 2013 through August 14, 2014
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2013) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Awards , P3 Challenge Area - Air Quality , P3 Challenge Area - Sustainable and Healthy Communities , Sustainable and Healthy Communities

Objective:

The use of sunlight has always been a major goal in the design and operation of commercial buildings to minimize electrical consumption of artificial lighting systems. Glazing systems designed to allow optimal visible light transmission also allow significant unwanted direct solar heat gain caused by infrared light. Conversely, glazing systems that are designed to reflect unwanted direct solar heat gain significantly reduce the transmittance of visible light through windows. The primary deficiencies of current glazing systems are their low transmission of visible light or high transmission of thermal solar radiation. While compromises between daylight transmittance and thermal performance are necessary when using traditional glazing systems and motivated by yet still high energy costs in buildings with glazed envelops, this research seeks to develop an advanced glazing with over 50% reduction in direct heat loads while maintaining over 90% visibility of the window glazing.

Summary/Accomplishments (Outputs/Outcomes):

Design Considerations and Conditions

A glazing unit with liquid fill (glycerin solution) of size 1.2 m by 1.2 m was chosen as the test specimen. The test box for the glazing unit was built of steel channel and Expanded Polystyrene insulation board with an R-Value of 20 to prevent heat losses. An adhesive caulk was used to seal the joints of the insulation board to prevent air leakage, thereby, focusing attention on the thermal performance of the glazing unit.

ASTM C119-12 was used as a guide in designing the experimental procedure. It provides the procedures for measuring the steady-state thermal transmittance of fenestration systems using the hot box method. The section 4.3 of the manual however, states that the test procedure can be used to test at other conditions other than the conditions described in the document for research purposes or product development.

This test method does not account for solar radiation effects so it has been modified to factor in solar infrared radiation. It will be done onsite where the glazing can have direct access to the infrared radiation of the sun in order to simulate the conditions expected from field installations. The thermal transmittance value that will be determined is a true experimental value but not a standardized thermal transmittance due to the modifications made to the experimental set up. The value computed can be compared with a reference glazing unit (thus, a glazing unit of the same dimension and material make but with an air fill) to validate the objectives of the project. The ASTM C119-12 was used together with ASTM 1492 to define the locations of the temperature sensors on the glazing unit to get accurate surface temperature measurements. The liquid fill to be used in the gap has been defined as a glycerine solution.

Project Status

1. The fluid performance criteria for optimal visible light transmittance with high opacity to infrared have been defined. The fluid that will be used is a glycerine solution.
2. Design and fabrication of the prototype for testing the new glazing began in November 2013 right after the funds for the project was released and it is completed.
3. Instrumentation to collect data for analysis has been ordered.

Challenges

Current simulation tools do not adequately analyse the model complex glazing used in this project.  Therefore; properties of the liquid solution will be characterized using in situ testing procedures to validate the performance.

Plan of Action

1. Validate in-situ performance of the glazing unit during summer.
2. Verify infrared absorption by the liquid solution in the glazing unit.
3. Provide an approach to improve infrared absorption for glazing manufacturing.
4. Re-evaluate the hot box test to account for infrared radiation.  

Conclusions:

Data collected from the test will be analysed and a Computational Fluid Dynamics model developed to study the characterization of the liquid fill. This will help to provide ways of improving the design and performance of fenestration systems. Initial modelling results show an 80% reduction in direct solar heat gain under static conditions.  Future research will translate this reduction into cost savings for highly glazed buildings under normal operating conditions. The activities that are to be performed next include; collection of data, analysis of data, Computational Fluid Dynamics analysis, energy simulation modelling for select reference building, and a comparative cost analysis for traditional and proposed glazing units. The anticipated end date of this research is August 14, 2014.

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this project

Supplemental Keywords:

Life cycle analysis, Conservation, Energy, Buildings