Engineering topics

Earle, Lieko

Publications and source records attributed to Earle, Lieko.

3 records

DOE OSTI2024

Connected Thermostat Alternatives for Room Air Conditioners and Minisplit Heat Pumps

The availability of smart, connected thermostats has improved climate control, energy efficiency, and grid demand-response programs for central HVAC systems. However, a significant gap exists in addressing integrated control systems for point-source heating and cooling systems such as window air-conditioners (window ACs) and mini-split heat pumps (MSHPs). This report examines the emerging market of third-party connected thermostats tailored for these systems, focusing on their effectiveness, reliability, and potential barriers to adoption.This study evaluates several commercially available products designed for room ACs and MSHPs through a series of laboratory tests. While these infrared-based (IR-based) thermostats offer remote temperature control and scheduling via mobile apps, our findings reveal that none are seamless, with reliability of basic functions being a critical factor. Promising features include integration of indoor air quality metrics and time-of-use pricing, but the latter are not yet available in the U.S. Barriers to broad user acceptance include non-seamless setup processes, challenges in thermostat placement, and unclear product differentiation. There is a pressing need for research and development in enabling MSHPs and central thermostats to coordinate, enhancing energy savings and comfort in retrofit applications. This study underscores the importance of further innovation in connected thermostat technology to address the diverse needs of single-zone HVAC systems and promote efficient energy management in households.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2024

Moisture Performance of Unvented Attics With Vapor Diffusion Ports and Buried Ducts in Hot, Humid Climates

Energy efficiency measures, such as cool roofs, radiant barriers, interior radiative control coatings, and buried ducts are increasing in popularity and are promoted by energy codes because of their energy-saving potential. However, these strategies can also pose moisture risks in attics by lowering surface temperatures and increasing condensation potential and moisture accumulation. Of particular concern in hot-humid climates is dripping condensation on cold air-conditioning ductwork in the summer - commonly referred to as duct "sweating" - which threatens the attic floor with conditions conducive to mold growth and rot. One strategy to mitigate these moisture issues is to wrap ductwork in thicker duct-wrap insulation with an integrated exterior vapor barrier, but thick duct wrap can be difficult to come by, expensive, and unwieldy to work with. This study explores an alternative strategy of reducing moisture issues while embracing energy efficiency by using unvented attics with vapor diffusion ports and buried ductwork in hot-humid climates. Vapor diffusion ports have been studied so far in a wide range of U.S. climates, mostly in the context of conditioned attics. In this study, the strategy is implemented in the novel context of hot-humid climates with ductwork sitting atop blown-in attic floor insulation in unconditioned attics. Using a combination of field experiments and hygrothermal modeling, the findings of this project indicate that an unvented attic with vapor diffusion ports and buried ducts may be a key part of a successful low-cost method for reducing the attic moisture load by venting excess moisture out of the attic, keeping duct-jacket surfaces above dew point temperature, and keeping the roof deck safe from winter moisture accumulation.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2024

Mapping use cases and dataset needs for benchmarking buildings data

A perennial challenge in buildings research is the lack of high-quality datasets that can be relied upon for a wide array of tasks, including model calibration and improving energy efficiency and load flexibility. Instrumenting a building for data collection is resource intensive, so it is important to be methodical in the approach and ensure that resulting data are flexible and useful for a broad range of analyses. This study aims to fill the gaps in characterizing potential use cases for buildings datasets and mapping them to dataset needs using a well-defined data infrastructure. Here, we have developed a systematic mapping strategy between buildings dataset needs and use cases to help streamline the processes of efficiently targeting datasets, designing building sensing systems, and determining buildings research use cases. We selected 14 prospective use cases and 11 refined buildings data categories for developing the preliminary dataset-needs-to-use-cases mapping matrix (‘DN-UC mapping matrix’) with generic ‘Tags’—a detailed sub-level of data categories extracted by justifying the needs of an aspect of the datasets to use cases. We present two example applications of the developed mapping matrix to demonstrate use of the mapping matrix and its effectiveness.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗