Multi-family Housing Complexes Research Articles

Modeling the resiliency of energy-efficient retrofits in low-income multifamily housing.

Residential energy efficiency and ventilation retrofits (eg, building weatherization, local exhaust ventilation, HVAC filtration) can influence indoor air quality (IAQ) and occupant health, but these measures' impact varies by occupant activity. In this study, we used the multizone airflow and IAQ analysis program CONTAM to simulate the impacts of energy retrofits on indoor concentrations of PM2.5 and NO2 in a low-income multifamily housing complex in Boston, Massachusetts (USA). We evaluated the differential impact of residential activities, such as low- and high-emission cooking, cigarette smoking, and window opening, on IAQ across two seasons. We found that a comprehensive package of energy and ventilation retrofits was resilient to a range of occupant activities, while less holistic approaches without ventilation improvements led to increases in indoor PM2.5 or NO2 for some populations. In general, homes with simulated concentration increases included those with heavy cooking and no local exhaust ventilation, and smoking homes without HVAC filtration. Our analytical framework can be used to identify energy-efficient home interventions with indoor retrofit resiliency (ie, those that provide IAQ benefits regardless of occupant activity), as well as less resilient retrofits that can be coupled with behavioral interventions (eg, smoking cessation) to provide cost-effective, widespread benefits.

A Study on the Suggestion of Community Facilities Model in Multi-Family Housing Complexes

A Study on the Suggestion of Community Facilities Model in Multi-Family Housing Complexes

Promoting Outdoor Spaces Design features to Increase User Satisfaction in Residential Area. Duhok City as case Study

The rapid development of the residential area in Duhok City and the new trend of housing policy towards high density and multifamily housing complexes affect the urban social life of the residents. The urban public open and green spaces in housing complexes create places for residents to come together and to strengthen their social networks. This research aims to investigate the outdoor space design approach in the new developed housing project (Avro city) as an example for high density multifamily housing complex due to its outdoor space design characteristics to identifying design features and elements that promote the quality of urban life and increase the user satisfaction in residential area. The researcher used qualitative data collection methodology using case study approach. The data collection method based on three sources namely the analytical study of the outdoor space design features from the available maps and site visiting, the on-Site observations of the residents, how they use the outdoor space, and the questionnaire survey results with the residents to measure their satisfaction about the outdoor space living environment. The findings of the research indicate that the design quality of the physical features such as landscape design, artificial water, landscape furniture, a proper pedestrian and greenery encourage people to use the outdoor space for social activities. Finally, the research provides guidelines for housing developers, urban designers and related governmental institutions to incorporate effective outdoor space design quality for successful urban living environment.

Development of a CO2 emission benchmark for achieving the national CO2 emission reduction target by 2030

To achieve the national CO2 emission reduction target (CERT) in the building sector established together with the launching of POST-2020, various countries are introducing the emission trading scheme (ETS), which is considered to have a considerable effect on CO2 emission reduction. Towards this end, it is important to establish a reasonable CO2 emission benchmark for the effective allocation of CO2 emission allowances. As the previous CO2 emission benchmark, however, was focused on the industry sector (e.g., power generation sector, manufacturing sector, etc.), it is difficult to apply to the building sector. To solve this problem, this study aimed to develop a CO2 emission benchmark for allocating CO2 emission allowances in multi-family housing complexes (MFHCs). This study was conducted in three steps: (i) establishment of the database; (ii) formation of clusters using a decision tree (DT); and (iii) development of the CO2 emission benchmark for MFHCs. The nine CO2 emission benchmarks (i.e., 0.03116-0.06667 tCO2/m2year) for MFHCs were developed using a DT based on the heating type and the elapsed years, and were validated using the Kruskal-Wallis test and t-test. It was shown that using the developed CO2 emission benchmark for MFHCs to calculate the national CO2 emission reduction in MFHCs satisfied the national CERT (18.1%). On the other hand, when the CO2 emission benchmarks for MFHCs calculated based on the South Korean ETS and the EU ETS, which were applied to the industry sector, were used, the national CO2 emission reduction was −5.29 and 45.55%, respectively. The proposed CO2 emission benchmark for MFHCs may be useful for policymaking for determining the allocation of CO2 emission allowances for achieving the national CERT.

Covariance effect analysis of similarity measurement methods for early construction cost estimation using case-based reasoning

Abstract Quality source data are essential to secure the reliability of early cost estimation, accuracy, and transparency of the estimation process. To improve the reliability of cost estimation results using CBR, a recurring issue in similarity measurement has been to accurately compute the distance among attributes and cases for the retrieval of the most similar singular or plural cases. However, these existing similarity measures have limitations in taking the covariance among attributes into consideration, and reflecting the effects of covariance in the computation of distances among attributes. To deal with this challenging issue, this research examines the weighted Mahalanobis distance based similarity measure applied to CBR cost estimation, and carries out comparative research on the existing distance measurement methods of CBR. To validate the suggested CBR cost model, simulation data test and case studies using 99 multi-family housing complexes are carried out. As a consequence, this research is expected to improve academic value and mathematical and statistical logicality of similarity measurement, especially in application to CBR cost estimation. The results can be further referenced to not only the area of construction cost estimation, but also international market selection, planning and scheduling, noise control and management, and energy management where case-based reasoning can be applied.

Development of Diagnostic Insecticide Concentrations and Assessment of Insecticide Susceptibility in German Cockroach (Dictyoptera: Blattellidae) Field Strains Collected From Public Housing.

Insecticide resistance in German cockroaches (Blattella germanica (L.)) has been a barrier to effective control since its first documentation in the 1950s. A necessary first step toward managing resistance is to understand insecticide susceptibility profiles in field-collected strains so that active ingredients (AIs) with lowest resistance levels can be identified. As a first step in this study, diagnostic concentrations (DCs) were determined for 14 insecticide AIs based on lethal concentrations that killed 99% or 90% of the individuals from a susceptible lab strain (JWax-S). Next, cockroaches were collected from two low-income multifamily housing complexes in Danville, IL, and Indianapolis, IN, and used to establish laboratory strains. These strains were screened against the 14 AI-DCs in vial bioassays, and susceptibility profiles were determined by comparing percent mortalities between the field strains relative to the JWax-S strain. Results revealed lowest resistance of field strains to boric acid, abamectin, dinotefuran, clothianidin, thiamethoxam, and chlorfenapyr. For the AIs hydramethylnon and imidacloprid, field strains did not display survivorship different than the lab strain, but >90% mortality was never achieved. Lastly, both field strains displayed resistance to indoxacarb, fipronil, acetamiprid, beta-cyfluthrin, bifenthrin, and lambda-cyhalothrin, but at varying levels. These results satisfy two objectives. First, baseline monitoring DCs were established for 14 insecticides presently registered for use against cockroaches, which represents a useful resource. Second, our findings reveal insecticide AIs with lowest resistance levels for use in forthcoming field studies that will investigate impacts of different insecticide deployment strategies on resistance management and evolution in cockroach field populations.

Disaster Capitalism, Housing Vulnerability, and the Tuscaloosa Tornado: A Critical Analysis of Rebuilding Efforts

In this paper, we assess how social vulnerability to disasters continued into the recovery phase following the April 27, 2011 Tuscaloosa tornado, particularly by examining how social class affected housing availability approximately three years after the storm. Data from multiple sources indicated that apartment complexes that were constructed to replace destroyed or damaged housing are generally demanding higher rents and have fewer units available than the complexes which existed before the storm. Additionally, even as a residential construction boom has occurred in Tuscaloosa following the storm, the new complexes are almost entirely marketed to the college student population, even though none of the multifamily housing complexes destroyed in the storm solely housed college students. These findings support a disaster capitalism model of recovery that has mainly focused on building high-end student housing, resulting in the perpetuation of vulnerability for lower-income, permanent Tuscaloosa residents. We discuss some of the potential consequences of the reconstruction of Tuscaloosa, and propose suggestions to reduce vulnerability in the rebuilding process for cities that have been decimated by natural disasters.

Improvements of the operational rating system for existing residential buildings

The Building Energy Consumption Certification (BECC) evaluating the energy performance of existing buildings has been launched since 2016 to reduce the operational energy consumption in existing buildings in South Korea. However, the current BECC has some potential problems, and these problems should be solved to evaluate the energy performance of existing building more accurately. Thus, this study aims to identify the potential problems in the current BEEC using the hypothesis testing. And then this study proposes the improved BECC using the energy benchmarking process and the modified grading process to solve the potential problems. As a result of the hypothesis testing based on the data of 504 multi-family housing complexes (MFHCs), the potential problems were identified as follows: (i) the current classification criteria caused the irrational judgements, and (ii) the current grading system was lacking in its assessment function (over 94% of MFHCs ranked in the average level as grades “C” and “D”). To solve these problems, this study proposed the improved BECC. The energy benchmarking process provides the reasonable classification criteria, and the modified grading process finds the reasonable number of grades and its range. The result of comparative analysis based on 504 MFHCs indicated that the improved BECC could solve the problems in the current BECC. That is, over 94% of MFHCs were ranked in grades “C” and “D” in the current BECC while they were shown in all five grades (i.e., grades “A”, “B”, “C”, “D”, and “E”) in the improved BECC. The policy-makers can more accurately assess the energy performance of existing MFHCs by using the improved BECC.

Development of a prediction model for the cost saving potentials in implementing the building energy efficiency rating certification

Building energy efficiency rating (BEER) certification is an energy performance certificates (EPCs) in South Korea. It is critical to examine the cost saving potentials of the BEER-certification in advance. This study aimed to develop a prediction model for the cost saving potentials in implementing the BEER-certification, in which the cost saving potentials included the energy cost savings of the BEER-certification and the relevant CO2 emissions reduction as well as the additional construction cost for the BEER-certification. The prediction model was developed by using data mining, life cycle cost analysis, real option valuation, and Monte Carlo simulation. The database were established with 437 multi-family housing complexes (MFHCs), including 116 BEER-certified MFHCs and 321 non-certified MFHCs. The case study was conducted to validate the developed prediction model using 321 non-certified MFHCs, which considered 20-year life cycle. As a result, compared to the additional construction cost, the average cost saving potentials of the 1st-BEER-certified MFHCs in Groups 1, 2, and 3 were predicted to be 3.77%, 2.78%, and 2.87%, respectively. The cost saving potentials can be used as a guideline for the additional construction cost of the BEER-certification in the early design phase.

Development of an integrated energy benchmark for a multi-family housing complex using district heating

The reliable benchmarks are required to evaluate building energy efficiency fairly. This study aims to develop the energy benchmarks and relevant process for a multi-family housing complex (MFHC), which is responsible for huge CO2 emissions in South Korea. A database, including the information on building attributes and energy consumption of 503 MFHCs, was established. The database was classified into three groups based on average enclosed area per household (AEA) through data mining techniques. The benchmarks of site energy use intensity (EUI), source EUI, and CO2 emission intensity (CEI) were developed from Groups 1, 2, and 3. Representatively, the developed benchmarks of CEI for Groups 1, 2, and 3 were 28.17, 24.16, and 20.96kg-CO2/m2y, respectively. A comparative analysis using the operational rating identified that the developed benchmarks could solve the irrationality of the original benchmarks from overall database. In the case of the original benchmarks, 93% of small-AEA-groups and 16% of large-AEA-groups received lower grades. In the case of the developed benchmark, the upper and lower grades in Groups 1–3 were both adjusted to 50%. The proposed process for developing energy benchmark is applicable to evaluate the energy efficiency of other buildings, in other regions.

Development of an evaluation process for green and non-green buildings focused on energy performance of G-SEED and LEED

This study aims to develop an evaluation process for comparing the energy performances of Green and non-Green buildings. The information on the building attributes and energy consumption of 455 multi-family housing complexes (MFHCs) in 2014, including 321 non-certified MFHCs and 126 MFHCs that accredited Green Standard for Energy and Environmental Design (G-SEED) certification (an official Green Building certification in South Korea) and 8 MFHCs that accredited Leadership in Energy and Environmental Development (LEED) certification, were applied to the empirical study. Data-mining techniques are applied to develop the comparison groups considering various building attributes, and the database was classified into four groups based on the average enclosed area per household (AEA). It was shown that the large-AEA groups (i.e., Group 4, over 143.47 m2) had less energy use intensity (EUI) than the small-AEA groups (i.e., Group 1, under 97.04 m2). The mean of site EUI for Groups 1, 2, 3, and 4 were significantly different (125.29, 116.35, 110.89, and 101.00 kWh/m2∙y, respectively). While the G-SEED- and LEED-certified MFHCs were considered to have up to 10 and 15% energy savings, respectively, compared to all non-certified MFHCs, the comparative analysis by the developed Groups 1, 2, 3, and 4 revealed that the G-SEED-certified MFHCs and the non-certified MFHCs had no significant differences in energy performance. Therefore, the energy performance rating system of G-SEED should be revised. The proposed energy performance evaluation process can also be useful in identifying the energy performance of other buildings.

Understanding Residential Needs of Single or 2-Resident Households with a Focus on Communal Amenities of Multi-Family Housing Complexes

Due to rapid socio-demographic changes in Korean society, the number of single or 2-resident households i.e. small households, are increasing at a faster rate than expected. This research aimed to achieve a clear understanding of the residential needs of small households, which are distinctively different from those of regular households created by blood relations. A survey was carried out to identify the general residential needs of small households, and their communal amenity needs. It was found that small households had clearly different residential needs compared to regular households; the needs were generally uniform among regular households, while small households showed significant differences according to socio-demographics, residential conditions, lifestyle and continuation period of households. Given this, small households were categorized into four subgroups and characterized by type, according to the specific residential needs and communal amenity needs of each subgroup. As a result, this research was able to empirically embrace previous researches, which were sporadically carried out on some subgroups of small households, and to formulate residential conditions that the residents of small households want, based on the understanding of their residential needs rather than simple socio-demographic characteristics.

Correlation Analysis of Site Planning Factor and Opening Rate

As the need of differentiated residential environment in a multi-family housing complex gradually increases, the right-to-view with open household units is being evaluated as an economic value. This preference for a view requires a plan unlike the existing south-oriented ones but securing the “orientation and view” with both views to the open space inside the complex and to the natural landscape outside. In the framework of analysis based on the statistics of actual research on indexes for each planning elements of 30 complex cases and the values of the open sight rates, this study analyzes which the site planning factors are highly correlated to the increase of openness indexes and mutually verifies the correlation of such openness indexes with each site planning factors. For quantitative analysis on the correlation between openness indexes and site planning factors, the study conducted factor analysis, deriving the interrelationship between variables, and multiple regression analysis, analyzing which factors influence the indexes.

Evaluation of solar hot water heating system applications to high-rise multi-family housing complex based on three years of system operation

This study evaluated three-year operation of solar hot water heating system installed in multi-family housing complex with 1179 households in 14 units. At first, since the size of systems for multi-families are large, position of the building services room and collector installation becomes a significant matter. In order to resolve this, three building services rooms for three or four units of households were planned and the solar collectors were integrated directly on the roof facing South at 22° degrees to the horizontal. The accumulated heat gain from three-year operation was 52% of the design baseline (4069GJ/year). The reason for this could be a low altitude angle of collectors from the architectural design. Moreover, hot water usage and breakdowns of the system were evaluated using detailed analyses of operation data for three years by considering seasonal factors. These results are expected to give valuable feedback for the future design and wide use of the systems, as well as update the design baseline. Lastly, compared to a conventional boiler(δ=85%), the system produced a positive environmental effect equivalent to a reduction in oil use of 71,907L/year, and reduced carbon emissions equivalent to 50.8 TC and 186.3 TCO2 the pay-back period for the system was expanded 5 years.

Bathroom wastewater treatment in constructed wetlands with planting, non-planting and aeration, non-aeration conditions

This study aims to examine the treatment of graywater (GW), especially bathroom wastewater, using subsurface-flow constructed wetlands (CWs) in an apartment complex. It analyzed the removal of organic matters and nitrogen, the status of a wetland by depth, and microbial communities under the conditions of aeration and non-aeration at the inlet section, and planting and non-planting. The results of this study show that aeration at the inlet section and planting affect ORP, SO42-, and nitrogen by water flowing distance and water depth in a wetland. The result of CODcr removal seems to satisfy the Korean standard (below 20 mg/L (CODmn)) of reuse water quality in all three operational conditions. The aeration at the inlet section has the advantages of effectively removing organic matters at the inlet section, thus preventing its clogging, and removing nitrogen through the nitrification. Aeration at the inlet section and planting are expected to have a positive effect on the wetland status and GW treatment. Therefore, aeration at the inlet and planting will be helpful to construct and operate an artificial wetland in residential areas such as a multi-family housing complex. Ammonia-oxidizing bacteria including Nitrosomonas, Nitrosospira, Nitrosococcus and denitrifying or nitrate-reducing bacteria such as Thiobacillus, Achromobacter, Pseudomonas, Micrococcus belong to the classes of β-proteobacteria, γ-proteobacteria, and Actinobacteria. These microbial communities found in this study seem to contribute to nitrogen removal. But, the roles of microbial community in CWs need to be further investigated, both qualitatively and quantitatively.

Framework for establishing the optimal implementation strategy of a fuel-cell-based combined heat and power system: Focused on multi-family housing complex

The fuel-cell-based combined heat and power system (FCCHPS) is attracting attention as a new/renewable energy system with great potential for coping with climate change. However, a FCCHPS has not been actively applied to building sector in South Korea. Therefore, this study aimed to develop a framework for establishing the optimal implementation strategy of a FCCHPS for multi-family housing complex (MFHC). The implementation strategy of a FCCHPS consists of the operating scheme and operating size. To verify the feasibility of the proposed framework, ‘O’ MFHC located in Seoul, South Korea was selected as a case study. ‘O’ MFHC was assessed from the perspective of primary energy saving (PES), and life cycle cost (LCC) and life cycle CO2 (LCCO2). In terms of PES, IS_PLF_500kW was determined as the optimal implementation strategy of a FCCHPS, where the operating scheme was power load following (PLF) and the operating size was 500kW. PES and its saving ratio were determined at 1476.8 TOE/year and 54%, respectively. In terms of LCC and LCCO2, IS_HLF_200kW was determined as the optimal implementation strategy of a FCCHPS, where the operating scheme was heating load following (HLF) and the operating size was 200kW. The net present value, its saving ratio, and break-even point were determined at US$ 3,823,091, 15.7%, and 3year, respectively. The proposed framework can be used for establishing the optimal implementation strategy of a FCCHPS depending on the energy demand of a given building and the government subsidy in introducing a FCCHPS to the building sector.

Decision support model for establishing the optimal energy retrofit strategy for existing multi-family housing complexes

The number of multi-family housing complexes (MFHCs) over 15yr old in South Korea is expected to exceed 5 million by 2015. Accordingly, the demand for energy retrofit in the deteriorating MFHCs is rapidly increasing. This study aimed to develop a decision support model for establishing the optimal energy retrofit strategy for existing MFHCs. It can provide clear criteria for establishing the carbon emissions reduction target (CERT) and allow efficient budget allocation for conducting the energy retrofit. The CERT for “S” MFHC, one of MFHCs located in Seoul, as a case study, was set at 23.0% (electricity) and 27.9% (gas energy). In the economic and environmental assessment, it was determined that scenario #12 was the optimal scenario (ranked second with regard to NPV40 (net present value at year 40) and third with regard to SIR40 (saving to investment ratio at year 40). The proposed model could be useful for owners, construction managers, or policymakers in charge of establishing energy retrofit strategy for existing MFHCs. It could allow contractors in a competitive bidding process to rationally establish the CERT and select the optimal energy retrofit strategy. It can be also applied to any other country or sector in a global environment.

Benchmarks as a tool for free allocation through comparison with similar projects: Focused on multi-family housing complex

A multilateral effort to reduce greenhouse gas (GHG) emissions has been implemented around the world. In particular, the Emissions Trading Scheme (ETS) emerged as a market-based approach used to control GHG emissions by providing carbon credits (or allowances). One of the most controversial issues in the ETS is the question of how the allowances will be distributed. Therefore, this research aimed to develop a decision support model for establishing benchmarks as a tool for free allocation in the construction industry. It can be used in the pre-design phase to estimate the amount of allowances in a given construction site. In this study, a total of 147 types of data on the reinforced concrete frame in multi-family housing projects in South Korea were collected and used to develop the advanced Case-Based Reasoning (CBR), which can be used to establish benchmarks as a tool for free allocation.Results showed that the prediction performance of the advanced CBR model was superior (prediction accuracy; standard deviation) in all classifications: concrete (93.45%; 6.01), steel bar (94.20%; 4.34), and formwork (94.28%; 4.67). In the case study, a total of 60 possible combinations were evaluated in terms of the economic and environmental impact simultaneously with the retrieved cases. The results of this study could be expanded into other areas including new renewable energy, rehabilitation projects, and demolition projects.

An Energy and Water Resource Demand Estimation Model for Multi-Family Housing Complexes in Korea

This paper proposes and develops a residential energy and resource consumption estimation model in the context of multi-family residential housing in Korea using a multi-layer perceptron (MLP) neural network. Eight indicators are introduced which affect the energy and water resource usage characteristics of Korean residential complexes. The proposed model precisely estimated the electricity, gas energy and water consumption for each examined residential complex. In terms of validation, the results showed the highest level of agreement with actually collected datasets. The model shows promising prospects in providing necessary estimations, not only for optimally scaling and sizing energy- and water-related infrastructures, but also to promote reliable energy and resource savings through greenhouse gas (GHG) reduction planning in multi-family housing complexes. The model could also be of use in framing guidelines for the better planning of national or regional energy and resource policies and for forming a foundation of decision-making with definite references regarding the facility management of each apartment complex to enhance the energy and resource use efficiency at these locations.

A decision support model for improving a multi-family housing complex based on CO2 emission from electricity consumption

The number of deteriorated multi-family housing complexes in South Korea continues to rise, and consequently their electricity consumption is also increasing. This needs to be addressed as part of the nation’s efforts to reduce energy consumption. The objective of this research was to develop a decision support model for determining the need to improve multi-family housing complexes. In this research, 1664 cases located in Seoul were selected for model development. The research team collected the characteristics and electricity energy consumption data of these projects in 2009–2010. The following were carried out in this research: (i) using the Decision Tree, multi-family housing complexes were clustered based on their electricity energy consumption; (ii) using Case-Based Reasoning, similar cases were retrieved from the same cluster; and (iii) using a combination of Multiple Regression Analysis, Artificial Neural Network, and Genetic Algorithm, the prediction performance of the developed model was improved. The results of this research can be used as follows: (i) as basic research data for continuously managing several energy consumption data of multi-family housing complexes; (ii) as advanced research data for predicting energy consumption based on the project characteristics; (iii) as practical research data for selecting the most optimal multi-family housing complex with the most potential in terms of energy savings; and (iv) as consistent and objective criteria for incentives and penalties.