Balancing Thermal Comfort and Energy Efficiency through Envelope Performance and HVAC Control
Limitations of Dry-Bulb Temperature–Based Control
DBT-based HVAC control assumes uniform thermal conditions within indoor spaces, neglecting the influence of surrounding surface temperatures. In practice, variations in wall, window, and façade temperatures—especially near building perimeters—create uneven radiant conditions. These discrepancies can result in localized discomfort for occupants, even when DBT setpoints are technically met.
Influence of Building Envelope Performance on Comfort
Field measurements conducted in two office buildings with differing insulation levels, window performance, and airtightness demonstrate the critical role of the thermal envelope. Buildings with weaker envelope performance exhibited significant radiant temperature differences between perimeter and core zones. These variations intensified thermal discomfort and increased reliance on HVAC systems to compensate for heat losses or gains.
Comparative Assessment of Operative Temperature Control
Building energy simulations were used to compare operative temperature (OT) control with traditional DBT control strategies. OT control, which integrates both air temperature and radiant temperature, was found to provide more uniform and improved thermal comfort conditions. By responding to radiant effects, OT-based strategies better reflect actual occupant thermal perception within indoor environments.
Energy Implications of Advanced HVAC Control Strategies
Despite comfort benefits, OT-based control was associated with increased energy consumption, particularly in buildings with poor envelope performance. In such cases, HVAC systems must work harder to counteract radiant heat losses or gains. However, when envelope performance is enhanced, the energy consumption gap between OT and DBT control narrows significantly, allowing comfort improvements without excessive energy penalties.
Retrofitting Strategies for Aging Building Stock
Given the large proportion of aging office buildings in South Korea with suboptimal thermal envelopes, this study highlights the urgency of targeted retrofit interventions. Upgrading insulation, adopting high-performance glazing, and improving airtightness are essential steps to reduce radiant temperature imbalances. When combined with advanced HVAC control strategies, these measures enable buildings to achieve a sustainable balance between thermal comfort and energy efficiency.
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