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• Air source heat pump fresh air unit with fresh and return air mixing was developed. • The supply air temperature deviation was within ±1 °C. • The heat pump COP was 2.46 when the outside temperature was −20.9 °C. • The heat pump COP was higher than that of the traditional heat recovery device. In order to ensure the indoor air quality of the building, in view of the problem of fresh air heating in severe cold regions, this paper proposes an air source heat pump fresh air unit with fresh air and return air mixing. The mixing process of the fresh air and return air is realized in the mixing box, which increases the inlet air temperature of the condenser, creates a suitable condensation pressure, and ensures the energy-saving and stable operation of the unit. In order to explore the operation effect, heating performance and energy saving of the unit, an experimental bench was built in Harbin for laboratory heating. The experimental results showed that when the return air volume was 1400 m3/h, the fresh air unit could operate continuously and stably under the conditions of ensuring the fresh air volume of 700 m3/h and the supply air temperature of 24.0 °C. When the outdoor temperature was 4.9 °C, the heat pump COP was 4.29. Even when the outdoor temperature dropped to −20.9 °C, the heat pump COP still reached 2.46, while the COP of the fresh air system combining electric preheating, heat recovery and air source heat pump was only 1.44, and the COP of the fresh air system combining electric preheating, heat recovery and electric heat was only 1.21. In addition, the heat pump COP increased with the increase of the return air volume. As the set temperature increased, the heat pump COP increased first and then decreased. [ABSTRACT FROM AUTHOR]

To investigate group differences in human perceptions, long-term and point-in-time measurements on indoor environmental parameters were conducted in 22 open-plan offices in Harbin, China and 1352 questionnaires were collected. The differences in human perceptions among gender, age, level of education, BMI and the location of subjects groups were analyzed. The comfort temperatures for the male subjects were 1.2 °C and 0.8 °C lower than those for the female subjects in summer and winter, which revealed the higher acceptance of female subjects to the higher indoor temperatures. The mean comfort vote for undergraduates was 0.7 higher than those for master and doctoral students in winter. The difference between Griffiths comfort temperatures and operative temperatures in the overweight group was 1.9 °C in summer and 2.5 °C in winter, higher than the normal weight group (1.8 °C and 2.1 °C) and the underweight group (1.3 °C and 1.7 °C), which revealed the lower tolerance of the overweight subjects to higher temperatures than other groups. The subjects who sat near windows had lower thermal comfort votes than the subjects at other locations in all seasons due to solar radiation, radiator heating and the draft caused by window opening. For indoor air quality, sound and light environment, the male subjects had higher comfort votes than those for female subjects, and undergraduates had higher comfort votes than master and doctoral students. Finally, the interaction of five groups on human comfort was also explored. This study can be used to take into account the difference between groups and decide the comfort systems. • Group differences in environmental quality in open-plan offices in a severe cold region were systematically analyzed. • The comfort temperatures for males were 1.2 °C and 0.8 °C lower than those for females in summer and winter, respectively. • The mean comfort vote for undergraduates was 0.7 higher than master and doctoral students in winter. • The sensitivity analysis of thermal sensation and the comfort temperatures among different groups was discussed. • Interaction of five groups (gender, age, etc.) on human comfort was explored. [ABSTRACT FROM AUTHOR]

This study analyzed the risk of exposure to volatile organic compounds (VOCs) in the apartment buildings (including bedrooms, living rooms, kitchens and study rooms) in Harbin, China. The concentration of total VOCs in bedrooms showed the lowest value with an average of 482.6 mg/m. 32.33 % of total measured VOCs correspond to aromatic hydrocarbons. The major chemical forms of the identified VOCs in other 3 types of rooms were alcohols which contributed to 30.66 % (in living rooms), 36.55 % (in kitchens) and 35.43 % (in study rooms) separately. Formaldehyde was the pollutant of highest concern given its high chronic toxic and carcinogenic risk levels according to the health assessment. Other pollutants of concern for human heal risks were benzene and naphthalene. The non-cancer risk by the exposure to naphthalene ranged from 2.39 to 2.80 in 4 target groups, which is more than 1.0 considered as a hazarded level to human health. [ABSTRACT FROM AUTHOR]

Human exposure to formaldehyde, toluene, xylene (FTX) and other volatile organic compounds (VOCs) are associated with negative health impact. To characterize the exposure and health effects of FTX and TVOC from indoor environments, we conducted an extensive monitoring campaign involving 1278 measurements of 472 indoor locations in Harbin, a megacity in China from May 2013 to March 2018. The results showed that household had the highest mean formaldehyde concentration (0.171 ± 0.084 mg m-3) among all types of indoor environments. Meanwhile, there was no significant differences in formaldehyde concentration of the living room, master bedroom, secondary bedroom and study room (p > 0.05), as well as toluene and xylene. The highest mean concentration of toluene, xylene and TVOC was measured in public bath center. Great difference was found between formaldehyde concentrations in 2013 and other years, except 2015. There were great positive nonlinear correlations between the indoor temperature and concentration of formaldehyde (p < 0.01), good negative nonlinear correlations between the finish time of decoration and concentration of formaldehyde (p < 0.01), good positive linear correlations between the relative humidity and concentration of formaldehyde (p < 0.01). A risk assessment methodology was utilized to evaluate the potential adverse health effects of the individual FTX compounds according to their carcinogenicities. The predicted carcinogenic risk of formaldehyde was greater than the threshold value 1E-06 at all environments. The non-carcinogenic risk of TX compounds in the population is negligible. For estimating human health risk exposure, sensitivity analysis showed that more attention should be given to the influential variables such as the level of pollutants. • SConducted an extensive monitoring campaign in Harbin, from May 2013 to March 2018. • There were correlations between the indoor temperature, relative humidity, finish time of decoration and concentration of formaldehyde. • The predicted carcinogenic risk of formaldehyde was greater than the threshold value at all microenvironments. [ABSTRACT FROM AUTHOR]