Thermal nonreciprocity plays a vital role in chip heat dissipation, energy-saving design, and high-temperature hyperthermia, typically realized through the use of advanced metamaterials with nonlinear, advective, spatiotemporal, or gradient properties. However, challenges such as fixed structural designs with limited adjustability, high energy consumption, and a narrow operational temperature range remain prevalent. Here, a systematic framework is introduced to achieve reconfigurable, zero-energy, and wide-temperature thermal nonreciprocity by transforming wasteful heat loss into a valuable regulatory tool. Vertical slabs composed of natural bulk materials enable asymmetric heat loss through natural convection, disrupting the inversion symmetry of thermal conduction. The reconfigurability of this system stems from the ability to modify heat loss by adjusting thermal conductivity, size, placement, and quantity of the slabs. Moreover, this structure allows for precise control of zero-energy thermal nonreciprocity across a broad temperature spectrum, utilizing solely environmental temperature gradients without additional energy consumption. This research presents a different approach to achieving nonreciprocity, broadening the potential for nonreciprocal devices such as thermal diodes and topological edge states, and inspiring further exploration of nonreciprocity in other loss-based systems. Nonreciprocity refers to the differing responses observed when processes occur in forward versus reverse directions. Thermal nonreciprocity is vital for applications such as chip cooling ( 1), waste heat recovery ( 2), high-temperature hyperthermia treatments ( 3), and energy-efficient material design ( 4). The asymmetric heat transfer achieved by thermal nonreciprocity can control the temperature of enclosed spaces and treat diseases through directional heat dissipation and directional heating respectively ( Fig. 1A). Through the use of metamaterials ( 5– 18), various functions of thermal nonreciprocity have been realized, including thermal diodes ( 19), transistors ( 20), logic circuits ( 21), and topological edge states ( 22, 23). Achieving thermal nonreciprocity often involves metamaterials with nonlinear ( 24– 29), advective ( 30– 37), spatiotemporal ( 38– 43), or gradient properties ( 44– 48). Despite these advancements, three major challenges hinder broader application. First, gradient materials can produce stable rectified outputs through simulated advection ( 44), yet their rigid structures lack the flexibility required for diverse practical applications. Second, while metamaterials influenced by convection or spatiotemporal modulation can effectively manage nonreciprocal heat transfer under external forces ( 31, 40), they typically require additional energy, making the pursuit of energy-free solutions highly desirable. Last, nonlinear materials, especially shape memory alloys, are excellent at maximizing rectification effects in unidirectional heat conduction ( 24), but their effectiveness is limited to temperatures near their phase transition points, restricting their usable temperature range. Addressing these challenges is crucial in advancing metamaterials science and thermal engineering to develop nonreciprocal thermal designs that are reconfigurable, operate without energy consumption, and function across a broad temperature range.