İÇ HAVA SICAKLIĞI VE OPERATİF SICAKLIK BAZLI HVAC SİSTEMLERİNİN ISIL KONFOR VE ENERJİ TÜKETİMİ BAKIMINDAN KARŞILAŞTIRILMASI

Isıtma, Soğutma ve Havandırma (HVAC) sistemlerinin ana amacı kullanıcılar için ısıl konforu sağlamaktır. Geleneksel olarak, HVAC sistemleri ısıl konforu sağlayabilmek için iç hava sıcaklığını sürekli ölçerek set-değerlerini ayarlar. Ancak, bir kabül edilebilir ısıl çevre standardı olan ASHRAE 55, iklimlendirilmiş binalar için operatif sıcaklık kabül aralıklarını kullanmayı önermektedir. Operatif sıcaklığın, iç hava sıcaklığı ve ortalama radyant sıcaklığın bir fonksiyonu olduğu düşünülürse, kullanıcıların nötr ısıl konforunun sağlanması için HVAC sistemlerinin set-değerleri operatif sıcaklığa göre kontrol edilebilir. Bu çalışma, biri operatif sıcaklık ve diğeri iç hava sıcaklığı bazlı aynı özellikteki iki oda bulunan aynı özellikteki iki HVAC sistemini ısıl konfor ve enerji tüketimi bakımından karşılaştırmaktadır. Örnek çalışma olarak, Ankara-Türkiye’de bulunan aynı mimari özelliklerdeki iki ofis odası seçilmiştir. HVAC sistemleri aynı zamanda ve aynı doluluk oranlarında ayrı ayrı operatif sıcaklık ve iç hava sıcaklığı bazlı kontrol edilerek çalıştırılmıştır. Sonuçlar, operatif bazlı HVAC sisteminin enerji tüketimini az da olsa arttırdığını fakat daha iyi ısıl konfor sağladığını göstermiştir. Bu çalışmanın sonuçları sadece enerji verimli HVAC sistemleri tasarlamak için değil, daha konforlu ortamlar yaratmak açısından da yol gösterici olacaktır.

COMPARISON OF INDOOR AIR TEMPERATURE AND OPERATIVE TEMPERATURE -DRIVEN HVAC SYSTEMS BY MEANS OF THERMAL COMFORT AND ENERGY CONSUMPTION

The main purpose of Heating, Ventilating and Air-Conditioning (HVAC) systems is to satisfy thermal comfort for theoccupants. Conventionally, HVAC systems adjust set-temperature to achieve thermal comfort by continuously measuringindoor air temperature of the environment. However, ASHRAE 55, a standard of acceptable thermal environments, offersto use acceptable ranges of operative temperatures in air-conditioned buildings. Considering operative temperature is afunction of indoor air temperature and mean radiant temperature, set-temperature of HVAC system can be controlled byusing operative temperature to satisfy neutral thermal comfort for the occupants. This study compares thermal comfortand energy consumption of two exactly same HVAC systems which are operated based on indoor air temperature andoperative temperature, respectively. Two office rooms with same architectural configurations -which are located in auniversity-Ankara-Turkey- were selected as a case study. The HVAC systems were operated based on indoor airtemperature and operative temperature, respectively, at the same time and occupancy schedules. The results showed thatoperative temperature driven controlled HVAC system achieves better thermal comfort while slightly increasing energyconsumption. The main findings of this study would be useful not only to design energy-efficient HVAC systems but alsocreate more comfortable environments.

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