The Effect of High Occupancy Density on IAQ, Moisture Conditions and Energy Use in Apartments

Abstract

Apartments built in Sweden during the record years 1961–1975 with the aim to remedy the housing shortage and abolish poor standards, were designed for a normal-sized family of 2–4 persons. The mechanical ventilation system, if existing, was primarily designed to ensure an air exchange in the apartment according to Swedish building regulations. During the last few years, the number of overcrowded apartments has increased due to housing shortage in general but also due to migration. Another aspect is that the ventilation in many apartments built during the record years is already insufficient at normal occupant load. The question is how doubling or tripling the number of occupants and thus, the moisture load will affect the risk of bad air quality and moisture damage. To find out, simulations were made to estimate whether it is possible to obtain sufficient air quality and low risk of moisture damage by only increasing the ventilation rates in existing systems or introducing new ventilation systems with and without heat recovery and what the consequence would be in terms of the additional energy demand. Measurements from earlier studies of CO2 and moisture supply in Swedish apartment buildings were used as input data.

Effect of Architectural Building Design Parameters on Thermal Comfort and Energy Consumption in Higher Education Buildings

“…According to Figure 15 the best orientation with the lowest thermal discomfort hours (379 h) was (θ = 85 • , θ = 265 • ), and the best orientation with the lowest energy consumption (50,430 kWh) was (θ = 175 • ), which were obtained based on PA. Previous studies [124,134,135] align with the result of this study regarding the effect of building orientation on both students' thermal comfort and building energy consumption. The building's orientation needs to be directed to the prevailing wind, and the presence or absence of natural ventilation has a significant impact [120,134].…”

“…In this study, the infiltration rate parameter had a positive influence on students' thermal discomfort (SRC = 0.0319) and energy consumption (SRC = 0.0525), as shown in Figure 13. Previous studies [124,125] explain the reason behind the adverse effect on thermal comfort in the event of an increase in the number of occupants and the direct effect on the increase in energy consumption. Mjörnell, Johansson [124] showed that extended occupancy density results in an increased moisture supply, depending on the number of people staying in the building.…”

The Performance Gap in Energy-Efficient Office Buildings: How the Occupants Can Help?

“…Signs of the performance gap as discussed in this research started appearing from the mid-1990s [48] and are still discussed as a core issue [20,40,49]. This gap is addressed in a diverse context in different studies, such as the difference between predicted and actual energy performance of a building, including all the complications of sub-systems, occupant behavior, atmospheric conditions, control settings, and others [5,27,28]. Tang et al [5] found that a primary energy saving between 36.7% to 48% is attainable by introducing a distributed energy system in buildings.…”

Impact of high residential density on the building technology, HVAC systems, and indoor environment in Swedish apartments

“…To force the ventilation to higher levels than the system is designed for is probably possible with existing fans, but it is likely to cause noise and draught indoors and will increase the energy use considerably. In cold climates, the ventilation energy use will approximately double if the residential load is doubled and the air change rate matches the load, but the absolute increase can be considerably reduced if heat-recovery is installed [7].…”