Browsing by Author "Salonen, Heidi, Prof., Aalto University, Department of Civil Engineering, Finland"

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  • Dynamic heating control in power and energy reduction and renovation of multifamily apartment buildings
    (2024) Hajian, Hatef
     School of Engineering | Doctoral dissertation (article-based)
    Energy renovation involves retrofitting existing buildings with energy-efficient technologies and introducing practices to reduce energy consumption, peak power, and greenhouse gas emissions. To support the renovation targets, this study has two objectives. First, it sought to conduct a comprehensive investigation of how dynamic heating control systems can reduce heating energy and power needs in existing buildings. This entailed evaluating the impact of reducing HC temperatures, developing a dynamic heating control algorithm, and integrating flow limiters into the heating system to enhance energy performance. Although there have been high expectations of potential energy savings achievable through dynamic heating control, our study revealed that actual energy savings may not be realized. However, significant reductions in peak power needs were quantified. This led to a study of sizing conditions to ascertain the extent to which smaller heat exchangers could be employed by implementing capacity limits through flow control. Second, the dissertation aimed to assess the efficacy of Finnish renovation practices based on Asumisen rahoitus ja kehittämiskeskus (ARA) renovation subsidies. This involved evaluating the effects of implementing various renovation packages on energy consumption in typical residential buildings in Finland, along with assessing the accuracy of Energy Performance Certificates (EPCs) and the actual energy savings achieved in the renovated buildings. Calibrated reference building simulation models validated with on-site measured data were used throughout the study. In the heating control analysis, lowering the HC temperatures resulted in a marginal energy saving of 0.6 kWh/m²a (equivalent to 0.8% of Space Heating (SH) energy) while maintaining the indoor air temperature at 21°C, revealing the almost nonexistent potential for energy savings. The developed dynamic control algorithm, enabling a reduction of the HC during domestic hot water peaks, led to a significant power reduction of more than 10% without compromising indoor air temperature. The introduction of the primary side flow limit reduced the heating sizing power and DH mass flow rate by 5.5% and 12.4%, respectively, under designed outdoor temperature conditions, enabling a more efficient use of DH system capacity. In the analysis of common renovation packages based on heat pumps and window replacements, it was noticed that official EPCs overestimated before the renovation energy use as well as energy saving by a factor of almost two because of heavily overestimated infiltration and ventilation. Renovations undertaken with ARA renovation grants generally showed good energy savings. However, typical support for about 25% of the total cost of shallow renovations dropped below 10% in a deep renovation, which was not economically feasible. These findings underscore the importance of enhancing the accuracy of EPCs in assessing energy performance.
  • Emissions of wooden interior materials
    (2022) Alapieti, Tuomas
     School of Engineering | Doctoral dissertation (article-based)
    The use of wood in construction has increased for environmental reasons, and wood has a number of properties that are potentially beneficial for indoor environment quality and human health. However, different wood species emit a wide variety of chemical compounds, and emissions from recently dried timber in particular can be considerable. To control emissions inside buildings, some factors related to wood emissions and their relationship with human perception require deeper knowledge. This dissertation aims to provide new knowledge about the chemical emissions of wooden interior materials under specific parameters. Additionally, the performance of indoor air quality (IAQ) sensors was studied. The effects of moisture content (MC) and paints on the emissions of pinewood boards were studied in laboratory test chambers. The test specimens consisted of uncoated wood samples at two MC levels (10% and 16%), wood samples of both MCs coated with three paints, and the three paints on glass plates were used as reference samples. The emission development of the samples was studied for 28 days. Emitted compounds and their concentrations from uncoated pinewood were consistent with previous studies. Painted wood samples showed high emissions of paint-based compounds that decreased rapidly with time, while the share of wood-based compounds in the emissions increased over time. Uncoated and painted wood samples had lower emissions of wood-based compounds with higher MC (16%) resulting mainly from lower emissions of terpene compounds. Additionally, higher MC decreased emissions of paint-based compounds. The measured and perceived IAQ was studied in three low-energy wooden test buildings (TBs) with three ventilation levels. Levels of total volatile organic compounds (TVOC) were remarkably higher in test building made of pinewood timber (TB 3) than in other buildings (TB1 and TB 2) built with 'lightweight' wooden structures, and the main difference in TVOC levels was terpene concentrations. TVOC levels decreased consistently in TB 3 with higher ventilation. TVOC levels also decreased in the other test buildings, but the effect of the ventilation was less clear, especially between the two highest levels. Perceived air quality improved systematically in all test buildings with higher ventilation, and the differences between the lowest and highest ventilation levels were statistically significant. Because of the increased availability and use of sensors for monitoring TVOC levels inside buildings, performance of four metal oxide semiconductor (MOS) and one photoionization detector (PID) sensors were studied in laboratory and field experiments. Both experiments showed differences in performance between the MOS and PID sensors and between the four MOS sensors. The results suggested that current sensor technology is not capable of monitoring TVOC values precisely, but the sensors could be used to monitor temporal variations of TVOC concentrations and human-based effluents.
  • Improving perceived indoor conditions using building information models and field data
    (2020) Halmetoja, Esa
     School of Engineering | Doctoral dissertation (article-based)
    Facility management (FM) is known as a rapidly developing business sector. Digitalisation appeared and big data emerged during the last twenty years, but however, the essential processes of FM are still poorly digitalised. Same concerns its sub-region the facility maintenance and operations (FMO). The business models are old-fashioned and poorly support the exploitation of open data. This study presents how data sharing enables the introduction of new business models in facility maintenance and operations. Indoor conditions are one of the most critical issues in the built environment. An essential indicator of indoor conditions is perceived indoor air quality (IAQ), which problems have arisen as a national challenge in Finland during the last years. IAQ problems are difficult to control with traditional FMO processes. Also, perceived indoor conditions are challenging to verify without a dense sensor net, and preventive measures cannot be taken without field data. The aim of this study is present a new way to collect, store, analyse and utilise the field data to improve the perceived indoor conditions. Building information models (BIMs) are widely utilised in the planning and construction processes, but not much in post-construction operations. In this research, the convenient way for post-construction use of BIM is defined. Besides, the BIM-based conceptual architecture for gathering, combining, analysing, distributing, and visualising of field data has described. That solution, named as the conditions data model (CDM), improves the pace and quality of services and enables entirely new services. The CDM also renews FMO's operation models and improves IAQ's management. Besides, new kind of business emerges, and previously undefined values for owner-operators, occupants, and property service companies materialise.The relevant literature was reviewed to form the theoretical background of the study. The existence, types and sources of the field data were considered, based on the literature on human-machine interaction (HMI) and human-building interaction (HBI). Also, empirical analyses using interviews, online surveys, heuristic evaluations and studies of raw material were conducted. The grounded theory (GT) method was used to construct theory from data, using comparative analysis. Finally, the essentials were conceptualised, and conclusions were drawn using inductive inference. The most important finding is that the combination of BIM and field data, created in this study, allows a whole new way of thinking. Property maintenance is transformed from a de-tail level workflow led by the subscriber into a knowledge-based activity, where the quality of the service is the most important factor. In the new operating model, the service provider obtains all the data from the building subscriber through a common platform. Accordingly, the service provider is expected to provide high-quality service to the subscriber and occupants.
  • Tracking diversity, metabolic activity, and bioactive metabolites of the building mycobiota – examples and novel findings
    (2022) Salo, Marja Johanna
     School of Engineering | Doctoral dissertation (article-based)
    Fungal growth in a building may cause decay of building materials and health effects on building users. Growth conditions affect the diversity of fungal species, the production of fungal metabolites, and the formation of guttation droplets, of which the contents and effects are still largely unknown. This study aimed to track the diversity and toxicity of the fungal species found in premises related to former moisture damages and health complaints of the occupants, demonstrate the guttation of metabolites by actively growing filamentous fungi, and design a method for detecting the transition of the fungal metabolites. In addition, the study aimed to evaluate fast microscopic and toxicological methods for monitoring metabolic activity in some common indoor fungi and to reveal the metabolic difference between fresh, actively growing, and old, desiccated, dormant colonies growing in building materials and culture media. Fungal colonies from the cultivated samples of the settled indoor dust and building materials were screened for toxicity and identified. Most individual colonies (>70% of tested colonies) in the samples collected from the rooms with indoor air-related health complaints proved toxic with the bioassays used. Many of the toxigenic species found in indoor settled dust were also detected in the insulation material of the building envelope next to the same room. Indoor isolates of Penicillium expansum, Acrostalagmus luteoalbus, and Aspergillus calidoustus, rarely or not earlier reported indoor, produced mycotoxins: communesins A, B, and D and chaetoglobosin C; melinacidins II, III, and IV; and ophiobolins G, H, and K and 6-epi-ophiobolin K, respectively. The guttation phenomenon was observed for toxigenic Pen. expansum, Acr. luteoalbus, Asp. calidoustus, and Chaetomium globosum. Pen. expansum formed guttation droplets even when growing on building material. The guttation droplets of Pen. expansum strain RcP61 (grown on MEA) were highly toxic, contained communesins A, B, and D (at the concentration of 86 µg communesins (in total) per mL of exudate) and chaetoglobosin C (480 µg toxin per mL of exudate), and proved to be more toxic than biomass extracts (containing 10 mg dry wt per mL) of the same strain. A simple test arrangement revealed the transition of the guttation droplets carrying conidia and secondary metabolites such as toxins, hydrophobics, and surfactants from mycelia to the inner surface of the lid of the Petri dish through the air. The transition of the mycotoxins communesins and chaetoglobosin A produced by an indoor isolate of Pen. expansum was confirmed using HPLC-MS analysis. Viability staining, illuminating with UV light, and bioassays revealed differences between dehydrated and actively growing fungal biomass. The old, dry dormant fungal biomass emitted less fluorescence after viability staining and UV excitation, contained fewer guttation droplets, and showed a weaker response in toxicity tests than the actively growing fungal biomass. This result indicates that the emissions of fungal metabolites into indoor air may depend on the metabolic state of the indoor filamentous fungi colonising a building.