The use of thermal insulation in building and equipment enclosures is a primary approach to reducing heating and cooling loads in buildings, which account for 42% and 24% of primary energy consumption in residential and commercial buildings, respectively. This project will yield the measurement science needed to accurately predict the insulating ability of these materials by developing reference materials and measurement techniques to allow for accurate assessment of the thermal properties of insulating materials.
Objective: To achieve reductions in heating and cooling loads in buildings by decreasing uncertainties in measurements of the thermal resistance of insulating materials by 2013 through the development of high-temperature measurement capabilities (i.e., either SRM and/or Calibration Service) and investigation of measurement techniques for novel insulating materials.
What is the new technical idea? The most cost effective means of reducing greenhouse gas emissions associated with building energy consumption is through the use of thermal insulation. Insulation in the building envelope and thermal devices, such as furnaces, boilers, refrigerators, and air-conditioning units, greatly reduce the need for heating and cooling the space, hot water, and other thermal processes. Accurate determination of the insulating capability of these materials is critical to achieve the energy savings that are expected. A vital aspect of the measurement system for thermal insulation is the availability of reliable methods for determining thermal properties of insulating materials. In this regard, one of the key challenges is the measurement uncertainty in thermal transmission properties of insulation materials at temperatures other than room temperature. NIST will address this problem through the development of reference materials that provide accurate thermal transmission values at elevated temperatures for use by testing laboratories in calibrating test equipment. Another key challenge is determining the insulating capabilities of innovative insulating materials. Novel insulating materials have been proposed to reduce heating and cooling loads in buildings, but the measurement science challenges have not been fully solved. Some materials with potential for greatly reducing energy consumption in buildings include phase change materials (PCMs), vacuum insulation panels (VIPs), and micro-porous materials, such as aerogels. NIST will initiate an effort to address the gaps in the measurement science needed to effectively implement these types of materials.
What is the research plan? The research plan for FY13 covers two related areas:
The process for reference material development and production is a multiyear effort culminating in a new thermal insulation reference material for extended temperatures, outlined below.
The focus in FY13 is on the pre-production stage. In FY12, NIST organized an interlaboratory comparison of the high-temperature guarded-hot-plate apparatus with the National Physical Laboratory (UK). In FY13, the analysis of these results will be completed. The analysis will assess the equivalence of the laboratories and assist in evaluating candidate reference materials. Additionally, a sensitivity study of the high-temperature hot plate will help bracket the measurement uncertainty. The key steps to be undertaken in FY13 to achieve a high-temperature reference material include measurements to assess the stability of the proposed material, characterization of the physical properties of the material, and testing to obtain the thermal conductivity over the desired temperature range. At the end of the year, NIST will have done the basic research to launch the production stage of a high-temperature reference material.
In FY12, a contractor to NIST assessed the technical viability of three categories of commercially-available advanced insulations, including PCMs, VIPs, and aerogels. The study concluded that VIPs have demonstrated good thermal performance and cost effectiveness and are a feasible alternative to traditional insulation materials. The thermal conductivity curve of porous materials typically decreases about 80%, or more, as the gas pressure is decreased. Additionally, it is surmised that pressure-dependent measurements can quantify the performance of another category of advanced insulation, aerogels. In FY13, NIST will continue to refine the measurement needs of advanced insulation and investigate the effect of pressure for thermal insulation materials experimentally and theoretically by modeling the mechanisms involved with the heat-transfer process. This study will continue to assist in the identification and solution of key measurement science challenges that must be overcome before such materials can assist in reducing thermal loads in buildings.
 “A Cost Curve for Green House Gas Reduction” The McKinsey Quarterly 2007, Number 1.
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Principal Investigator: Robert R. Zarr
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