In order to quantitatively assess how energy-efficient a building can be with regard to building design, the author would like to propose an energy-efficiency factor in buildings (K_hqnl) and a calculation formula for this factor. The actual thermal building calculations show that 86% of the overall heat transfer in a building comes through windows. Therefore the coefficient K_hqnl depends largely on the sun-shading capacity of the windows that can be roughly calculated as energy efficiency factor of the window. The author will also address 6 main architectural characteristics of an energy-efficient building concept in Vietnam.

The energy used in the buildings in subtropical and tropical countries is mainly for the cooling load requirements for air conditioning in summer, which is evaluated by OTTV value. To ensure a satisfactory OTTV value, the top priority of building envelope designing is reasonable WWR with appropriate sun shading devices to reduce the heat penetrated through window glass into the buildings. Therefore, the accurate calculation of solar radiation through window glass with shading devices is very important. The research aims to calibrate the reduced solar radiation coefficient of the shading device (β) from the original method, thereby completing the OTTV evaluation method with high accuracy. The calculation is based on the sunlight projection to determine the window’s shaded area created by shading devices of any shapes with consideration of diffuse radiation diminished. The results of β calculated showed that in tropical climate, the total solar radiation on the window glass is much lower than the previous method. A computer software built from the proposed theory helps the designer easily choose the optimal sun shading solutions. The research conducts the calculation as an example for horizontal-inclined and the combined of horizontal and left/right vertical shading devices.

Thermal comfort and air quality are basic factors of indoor environment. In office buildings, poor indoor air quality (IAQ) and low thermal comfort level may negatively affect occupants’ health and performance and eventually causes Sick Building Syndrome (SBS). In this research, the IAQ and thermal comfort were examined at a number of office buildings in the three Vietnamese cities of Hanoi (North), Danang (Central) and Ho Chi Minh City (South), which aims to assess the quality of indoor environment of office buildings in Vietnam. The results showed that the design and operation scheme play an important role for the achievement of the indoor air quality and thermal comfort. The collected data from field measurement and survey are expected to be concrete scientific basis for the revision of current standards and development of new standards in air quality of office buildings

Essential oils from Syzygium aromaticum (Myrtaceae) were extracted through hydrodistillation method, which applied in different fields such as relieve pain, promote healing, and aromatherapy industry. In this study, essential oil of clove buds was obtained using hydrodistillation method and evaluated for chemical compositions and physico-chemical characteristics. The averaged physico-chemical parameters were determined as specific gravity (1.0203 g/cm3), acid index (21.984), ester index (34.92). Moreover, the hydrodistillation process performance achieved by 6.85%. The composition of essential oils was analyzed by GC-MS, revealing a total of 15 volatile constituents existing in the Syzygium aromaticum oil. The major components were eugenol (76.542%), caryophyllene (4.319%), α-caryophyllene (0.456%), acete-ugenol (18.11%), caryophyllene oxide (0.192%), 4,4-dimethyl tetracyclo[6.3.2.0.(1,8)]tridecan-9-ol (0.12%). Syzygium aromaticum essential oil in this study was found to inhibit five bacteria strains including Bacillus cereus, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa. The highest antimicrobial activity of clove essential oil was found for Bacillus cereus strain (14 mm).