Objectives: The goal of this study is twofold: (1) identifying design strategies that enhance efficiency and support teamwork in emergency departments (EDs) and (2) identifying design features that contribute to the spread of COVID-19, based on staff perception. Background: Due to increasing ED visits annually, an efficient work environment has become one of the main concerns in designing EDs. According to the literature, an efficient work environment and teamwork improve healthcare outcomes and positively impact staff satisfaction. During the COVID-19 pandemic, EDs faced various changes such as workflow and space usage. Few studies explored staff perceptions about the influence of design features on efficiency, teamwork, and the COVID-19 spread. Method: An online survey with 14 open- and closed-ended questions was distributed among ED staff members to collect data about unit design features that impact efficiency, teamwork, and the COVID-19 spread. Results: The central nursing station was one of the preferred configurations that increased efficiency and teamwork in EDs. Decentralizing disposal rooms in small-size EDs and decentralizing the medication room in large-size EDs with more than 65 exam rooms can decrease staff walking steps. Flexibility to expand treatment spaces on demand, one-way track circulation path, and changing the air pressure in COVID-19 treatment areas were some of the staff suggestions for future EDs. Conclusion: The findings of this study contribute to the body of knowledge that EDs' physical environments can impact efficiency and teamwork among staff and, consequently, healthcare outcomes. Compartmentalization of the ED layout can reduce the spread of COVID-19.