• Energy Research

Net zero energy buildings (NZEBs) are energy efficient buildings that incorporate renewable energy generation systems so as to produce sufficient renewable energy to at least offset the total amount of non-renewable energy used by the building on an annual basis. NZEB technologies have widespread commercial and residential application, but their feasibility and efficacy in the livestock sector in support of sustainable intensification have received little attention. This study quantifies the potential for such technologies to improve sustainability outcomes in the livestock sector based on an ISO 14044-compliant life cycle assessment of a pilot net zero energy laying hen facility in Alberta, Canada compared to a conventional facility. It was found that direct energy inputs account for 6.47% and 31.64% of the life cycle cumulative energy use of egg production in NZE and non-NZE hen housing, respectively. Average infrastructure-related contributions to the life cycle impacts of egg production are only 4.34% and 1.94% for the NZE and non-NZE barns, but NZE technologies reduce the net impacts of egg production by 0.89–64.82%. The environmental impact payback time for the NZE barn (30-year lifespan) ranges from 1.38 to 20.66 years, considering the largely fossil fuel-based electricity grid in Alberta, which indicates that non-trivial environmental benefits would accrue across impact categories considered. However, this could vary considerably elsewhere depending on the types and amounts of green energy utilized in regional grid mixes. The type and availability of renewable energy resources that are integrated into NZE barns will similarly be important in determining the potential of such technologies to support sustainable intensification in this sector.

Abstract The livestock sector is a key source of greenhouse gas emissions and other impacts. Poultry (meat and eggs) is the fastest growing livestock sector globally. Poultry housing, including both infrastructure and operating energy, may account for as much as 50% of the total non-renewable energy (non-RE) use and up to 20%–35% of some of the life cycle impacts of poultry production. The application of net zero energy (NZE) building technologies (i.e. that enable net zero non-RE consumption on site) for poultry housing represents a promising but under-considered mitigation strategy, which could help lessen reliance on fossil fuels and reduce greenhouse gas (GHG) emissions. Insights from commercial and residential net zero energy building (NZEB) research can, to a limited extent, inform design considerations for NZE poultry housing, but a variety of unique design considerations and challenges inherent to confined, intensive animal husbandry must be considered. Towards this end, this review seeks to: 1) identify insights from research of residential and commercial NZEBs that might be applied in designing NZE poultry housing; 2) quantify the magnitude and distribution of energy use in poultry housing in order to determine key energy consuming components; and 3) identify priority design considerations for NZEBs for intensive confined poultry production, taking into account the physiological requirements of poultry as well as specific requirements for intensive, confined production. To accomplish these goals, 249 relevant papers were identified and reviewed. It was found that, similar to commercial/residential applications, design strategies should focus on a combination of aspects respectively aimed at (1) reducing direct energy (DE) use via structural design, (2) improving the energy efficiency of active technology systems and (3) installing context-appropriate renewable energy (RE) generation systems. Some common passive design strategies like maximizing glazed area may be less applicable for poultry housing where photoperiod control is required. Heating (during heating seasons) and ventilation (during cooling seasons) are the two main contributors to DE use in poultry housing but vary considerably based on geography and climate. HVAC systems should hence be a priority focus, considering the high ventilation rates required in confined poultry housing in order to maintain air quality. However, any modifications to current technologies should be based on careful consideration of the physiological requirements of poultry (for example, ambient temperature, air quality, feed and water provision, etc.), along with local climatic factors, technical feasibility and availability of alternative technologies, as well as both environmental and economic payback times.