Renovation of commercial buildings was studied to analyze typical energy improvements and to determine the performance gap in relation to major NZEB level renovation. To provide input for Estonian long-term renovation strategy, building samples and interviews were used to study how the commercial property companies deal with the building renovation need in Estonia. Results show that in office buildings renovations improved energy performance marginally and a performance gap of about 40% existed after market-based renovation. About one third of trade buildings reached the NZEB level, but within the rest, the performance gap was about 50%. A common renovation cost was around 10 €/m², but major renovation will need 130–150 €/m². The main obstacle was the long, 20–30-year payback time and uncertainty of the measures for major renovation. This increases the risk of investment for a real estate company preferring max 10-year payback time. Interviewees pointed out, that tenants are not motivated to invest because the expected 2–3% saving in the sum of rental and energy cost seems invisible. To start the NZEB renovation, building owners recommended preparation of new energy or carbon taxes together with incentives and knowledge about energy efficient renovation.

对商业建筑的改造进行了研究，以分析典型的能源改进并确定与主要 NZEB 级别改造相关的性能差距。为了为爱沙尼亚的长期翻新战略提供投入，我们使用建筑样本和访谈来研究商业地产公司如何应对爱沙尼亚的建筑翻新需求。结果表明，写字楼改造对能源性能的改善幅度很小，市场化改造后的性能差距约为40%。大约三分之一的贸易建筑达到了 NZEB 水平，但在其余建筑中，性能差距约为 50%。常见的翻新成本约为 10 欧元/m ²，但大型翻新需要 130–150 欧元/m ². 主要障碍是 20 至 30 年的长期投资回收期和重大改造措施的不确定性。对于更喜欢最长 10 年投资回收期的房地产公司来说，这增加了投资风险。受访者指出，租户没有动力投资，因为租金和能源成本总和中预期的 2-3% 的节省似乎是无形的。为了启动 NZEB 改造，建筑业主建议准备新能源或碳税，以及有关节能改造的激励措施和知识。