Theoretical Minimum Thermal Load in Buildings

Abstract

Building cooling and heating accounts for a large portion of total global energy use and requires commensurate amounts of resources, which contribute significantly to global warming.Traditionally, addressing this issue has meant improving the efficiency of equipment supplying the thermal energy, reducing envelope heat transfer, and reducing air infiltration. However, this approach is already reaching practical limits. In this perspective, we explore (1) theoretically how to reduce thermal load in buildings and (2) practically how to achieve that reduction and dramatically lower the energy required to support building loads. First, we discuss our framework developed for calculating the theoretical minimum thermal load (TMTL) in buildings. Our analysis shows that current thermal loads in buildings are more than an order-of-magnitude higher than the TMTL. We also introduce an approximate formula to calculate energy savings from zonal control of thermal load, which shows that the majority of zonal control benefits can be achieved with fewer than 10 zones. Then, we discuss pros and cons of various approaches and strategies to achieve the TMTL. We conclude our perspective with some longer-term R&D ideas such as thermally adaptive clothing and thermal storage to help approach the TMTL while providing the additional benefit of interacting with the renewable grid of the future. operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308 and by Lawrence Berkeley National Laboratory under Contract No. DE-AC02-05CH11231 with the U.S. Department of Energy Building Technologies Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes This document was prepared as an account of work sponsored by the United States Government.

Thermal fluids with high specific heat capacity through reversible Diels-Alder reactions

“…Approximately 90% of the world's current energy technologies involve thermal processes ( Henry et al., 2020 ). Examples include conversion of solar energy to heat ( Sharma et al., 2017 ), conversion of waste heat to electricity ( Hung, 2001 ), thermal storage ( Woods et al., 2021 ), cooling and heating of buildings ( Booten et al., 2021 ), and thermal management of various energy devices such as batteries ( Xia et al., 2017 ), microelectronics, and electrical transformers ( Meshkatodd, 2008 ). For example, there is significant interest in using solar thermal processes to decarbonize industrial heating; it is expected that industrial processes requiring medium temperature (<∼150°C) heat can be economically decarbonized using solar thermal processes.…”

Flexible engineering of advanced phase change materials

“…Similarly, the thermal management devices of the human body in hot or cold environments are also crucial to human health. Various personal body heating/cooling technologies, such as photo heating, electric heating, ice cooling, water cooling, and air cooling, have been developed ( Booten et al., 2021 ; Florindo et al., 2018 ; Hsu et al., 2017 ; Sipponen et al., 2020 ; Yang et al., 2017 ). However, these thermoregulation technologies usually restrict the mobility of the human body because of the heavy and complex wearable devices.…”

Oscillating Gadolinium Thermal Diode Using Temperature‐Dependent Magnetic Forces

“…Passive one‐way transmission of heat flow allows a thermal system to be coupled to its surroundings in the forward mode and decoupled in the reverse mode without the need for an active thermal control system. Thermal diodes have been studied for applications including waste heat scavenging systems, [ 4–6 ] electro/magnetocaloric [ 7,8 ] and thermoelectric [ 9 ] refrigeration cycles, thermal regulation of buildings, [ 10,11 ] prevention of permafrost melting under pipelines, [ 12 ] and solar thermal energy storage. [ 13,14 ] These applications require a demanding combination of high γ, relevant operating T range, convenient form factor, rapid time response, minimal hysteresis, minimal cost, and reliability upon thermal cycling, which motivates research into novel rectification mechanisms and devices.…”

“…electro/magnetocaloric [7,8] and thermoelectric [9] refrigeration cycles, thermal regulation of buildings, [10,11] prevention of permafrost melting under pipelines, [12] and solar thermal energy storage. [13,14] These applications require a demanding combination of high γ, relevant operating T range, convenient form factor, rapid time response, minimal hysteresis, minimal cost, and reliability upon thermal cycling, which motivates research into novel rectification mechanisms and devices.…”