In this paper, we explore the intersection of privacy, security, and environmental sustainability in cloud-based office solutions, focusing on quantifying user- and network-side energy use and associated carbon emissions. We hypothesise that privacy-focused services are typically more energy-efficient than those funded through data collection and advertising. To evaluate this, we propose a framework that systematically measures environmental costs based on energy usage and network data traffic during well-defined, automated usage scenarios. To test our hypothesis, we first analyse how underlying architectures and business models, such as monetisation through personalised advertising, contribute to the environmental footprint of these services. We then explore existing methodologies and tools for software environmental impact assessment. We apply our framework to three mainstream email services selected to reflect different privacy policies, from ad-supported tracking-intensive models to privacy-focused designs: Microsoft Outlook, Google Mail (Gmail), and Proton Mail. We extend this comparison to a self-hosted email solution, evaluated with and without end-to-end encryption. We show that the self-hosted solution, even with 14% of device energy and 15% of emissions overheads from PGP encryption, remains the most energy-efficient, saving up to 33% of emissions per session compared to Gmail. Among commercial providers, Proton Mail is the most efficient, saving up to 0.1 gCO2 e per session compared to Outlook, whose emissions can be further reduced by 2% through ad-blocking.

翻译：本文探讨了云端办公解决方案中隐私、安全与环境可持续性的交叉领域，重点量化用户端与网络端的能源消耗及相关碳排放。我们假设注重隐私的服务通常比通过数据收集和广告获利的服务更具能源效率。为验证此假设，我们提出一个框架，通过在明确定义的自动化使用场景中系统测量基于能源消耗和网络数据流量的环境成本。为检验假设，我们首先分析底层架构与商业模式（例如通过个性化广告变现）如何影响这些服务的环境足迹。随后，我们探讨现有软件环境影响评估的方法与工具。我们将该框架应用于三种主流电子邮件服务——选择依据是其隐私政策差异，涵盖从广告支持的高追踪模式到注重隐私的设计：Microsoft Outlook、Google Mail（Gmail）和Proton Mail。我们将此比较扩展至自托管电子邮件解决方案，并评估其在启用与未启用端到端加密时的表现。研究表明，即使PGP加密带来14%的设备能耗与15%的排放开销，自托管解决方案仍保持最高能效，相比Gmail每会话可减少高达33%的排放。在商业服务商中，Proton Mail能效最高，相比Outlook每会话可减少0.1 gCO2 e排放；而Outlook通过广告拦截可进一步降低2%的排放。