Multi-family Buildings Research Articles

Renewable Energy Source (RES)-Based Polygeneration Systems for Multi-Family Houses

This research work synthetizes the energy, economic, and environmental aspects of a novel configurational analysis of four polygeneration schemes designed to fulfill the demands of a multi-family building that includes 12 dwellings. The design aims to meet the requirements (water, electricity, heat and cold air) from Renewable Energy Sources (RESs), in particular by selecting photovoltaic and photovoltaic-thermal panels, thermoelectric generators, and biomass as auxiliaries. Electricity is available from the grid, and no electrical storage is planned. Water and cooling may be produced by alternative technologies that configure the polygeneration alternatives. The case study is in Valencia, a coastal Mediterranean city in Spain. The Design Builder Clima estimated demand calculations, and the system performance was modeled in TRNSYS. Desalination was linked by using EES models. Results show that the suggested schemes offer substantial energy and CO2 savings. The innovative life-cycle analysis applied further enhances the cumulative CO2 savings across the four configurations if the impact of the installations is compared with the conventional external supply. The electric option (combining heat pump and reverse osmosis for cooling and desalination) emerged as the most appealing solution due to its reliability, lower investment cost, and environmental impact.

Financial Aspects of Sustainable Rainwater Management in Small-Scale Urban Housing Communities

Sustainable rainwater management may counteract the effects of climate change and significantly improve the distorted water balance in urbanized catchments. However, despite the hydrologic advantages of rainwater management, acceptance and willingness-to-pay in the local society are required. This paper presents an assessment of the financial aspects, i.e., the cost-efficiency and economic feasibility, of various designs of rainwater management for a small-scale urban housing community in Lublin, Poland. The research was performed for a housing community covering approx. 1.38 ha and five multi-family residential buildings. The proposed designs covered rainwater harvesting systems, supported with extensive green roofs, with rainwater retained in underground or above-ground reservoirs, used with variable demand for watering the green areas and for underground parking lot flushing. For each designed variant, the investment as well as operation and maintenance costs were estimated. The assessment of the cost-efficiency and profitability of the proposed rainwater management systems was based on three indicators: Dynamic Generation Costs, Payback Period and Benefits–Costs Ratio. The performed calculations showed that only two designs, utilizing above-ground rainwater reservoirs, could be assessed as economically profitable. Thus, local communities may be unable to financially sustain investments in sustainable rainwater management, so it seems that financial support is required.

A holistic two-stage decision-making methodology for passive and active building design strategies under uncertainty

In the last decade, many studies focused on finding optimal design solutions considering trade-offs between different aspects of building design. Accordingly, multi-objective optimization (MOO) approaches have been increasingly applied in the building industry. However, certain aspects must be deepened to ensure a more effective decision-making process in the early planning phase. On the one hand, uncertainties should be considered before making decisions to ensure the robustness of the optimal solutions; on the other hand, decisions are made at different times in building planning, and the sequential order of making decisions should be modeled. This paper presents a holistic two-stage multi-objective stochastic optimization (MOSO)-II framework to minimize the environmental impact of global warming potential (GWP) and cost throughout the entire life cycle of a building (phases of A1-A3, B4, B6 and C3-C4), considering passive and active design strategies in two consecutive stages, under uncertainty. Herein, individual/use and political/market uncertainties are considered. As a proof of concept, the proposed framework is applied in a case study for a generic zone in a multi-family terraced residential building type with solid brick construction. The advantages of the proposed framework are validated by comparing it with alternative single-stage MOSO frameworks. Results show that the proposed two-stage MOSO-II framework can deliver a smaller range of solutions with a better performance in terms of lower GWP and cost. It indicates that the proposed framework can effectively assist planners in decision-making by reducing the effort in choosing the proper solution. Secondly, the results also emphasize the importance of passive design strategies in sustainable building planning. In addition, the energy mix structure and cost of energy sources should be carefully adjusted in the future to promote a more ecologically sustainable building design.

Modeling post-disaster recovery: Accounting for rental and multi-family housing

Post-disaster housing recovery models increase our understanding of recovery dynamics, vulnerable populations, and how people are affected by the direct losses that disasters create. Past recovery models have focused on single-family owner-occupied housing, while empirical evidence shows that rental units and multi-family housing are disadvantaged in post-disaster recovery. To fill this gap, this article presents an agent-based housing recovery model that includes the four common type–tenure combinations of single- and multi-family owner- and renter-occupied housing. The proposed model accounts for the different recovery processes, emphasizing funding sources available to each type–tenure. The outputs of our model include the timing of financing and recovery at building resolution across a community. We demonstrate the model with a case study of Alameda, California, recovering from a simulated M7.0 earthquake on the Hayward fault. The processes in the model replicate higher non-recovery of multi-family housing than single-family housing, as observed in past disasters, and a heavy reliance of single-family renter-occupied units on Small Business Administration funding, which is expected due to low earthquake insurance penetration. The simulation results indicate that multi-family housing would have the highest portion of unmet need remaining; however, some buildings with unmet needs are anticipated to be able to obtain a large portion of their funding. The remaining portion may be filled using personal financing or may be overcome with downsizing or downgrades. Multi-family housing would also benefit the most from Community Development Block Grants for Disaster Recovery (CDBG-DR). This benefit is a result of modeling the financing sources, that CDBG-DR is available, and that many multi-family buildings do not qualify for other sources. Communities’ allocation of public funding is important for housing recovery. Our model can help inform and compare potential financing policies to allocate public funds.

Weather Forecast Control for Heating of Multi-Family Buildings in Comparison with Feedback and Feedforward Control

Our joint environmental and energy commitments mean we must reduce the building’s energy use. Improved central heating control can play a role in how this is accomplished. There are three common control strategies: feedforward (traditional), feedback, and model predictive control (MPC). The latter two often work in parallel, where feedback uses indoor temperature sensors to adjust the supply water temperature. In contrast, the supply temperature setpoint is continuously calculated in MPC, fed with weather forecasts. The weather forecasts are often highlighted as essential ingredients in MPC, but at the same time, it is emphasized that temperature sensors are used to ensure a pleasant indoor temperature. To an outside observer, it is difficult to determine what is what in such combined control arrangements. Is energy saved because of the room sensors or because of the model? And what role do the weather forecasts play? This study quantifies the impact of the control strategy on energy use and indoor temperature. It concludes that PI-based feedback heating control saves approximately as much energy as MPC, and weather forecasts do not save significantly more energy than real-time weather data but are easier to obtain. The overall results for both control strategies align with the lower end of the result ranges of previous studies. The novelty is that the impact of weather forecasts has been studied separately and that different control strategies are compared against each other based on a model of a typical Swedish multi-family building.

The bidirectional substation for district heating users: experimental performance assessment with operational profiles of prosumer loads and distributed generation

The regulatory European and national policies outline the role of efficient district heating in achieving mid and long-term decarbonization targets. Prosumers could be equipped with bidirectional exchange substations to increase the local production contribution. The present paper evaluates the contribution of a bidirectional substation in maximizing the use of thermal energy produced locally by renewable sources or waste heat in a densely populated area, considering the limitation due to the non-contemporaneity of production and consumption and possibilities to overcome them. The substation prototype and the control system were tested in operational conditions, assuming the district heating network operating at two temperature levels (80 °C/50 °C and 60 °C/30 °C for supply and return) and applying the hardware-in-the-loop technique for coupling the substation in real-time with data-driven thermal loads (multi-family residential building) and production (solar panels and waste heat) profiles. The various energy flows in the substation are presented for representative days, resulting in a district heating contribution to the user’s load ranging between 99.8 % (winter day) and 21.8 % (summer day). The net-metering mechanism was considered, and the assessment extended to the entire year. The local production contribution to the user’s load ranges between 24 % and 100 %, depending on the system configuration considered.

Evaluating the IAQ and energy performance of ventilation systems in multifamily buildings

Buildings must provide Indoor Air Quality (IAQ) to the best of their ability while maintaining high energy efficiency. Mechanical ventilation systems are central to this concern. Despite the promises of innovative technologies in the market, a simple simulation tool for comparing their effects is not available. This article presents a TRNSYS-CONTAM co-simulation tool that enables the calculation of interdependent effects of temperature, moisture, and airflow on contaminant transport, and energy use on the building scale. The impact of the outdoor conditions, airtightness of building envelopes, neighboring environments, and the building’s wind exposure is also considered. IAQ is assessed by humidity, CO2 concentration in the building, and the exposure of its occupants to PM2.5 and formaldehyde concentrations to comply with available recommendations. This paper presents the methodology employed to evaluate the global performance of ventilation systems in terms of energy efficiency and IAQ.

“En-Solex”: A Novel Solar Exoskeleton for the Energy-efficiency Retrofitting of Existing Buildings

The energy retrofitting of the existing building stock is one of the current challenging strategic objectives on the way to the European target of climate neutrality by 2050. According to the Renovation Wave plan, around 35 million existing buildings need to be upgraded to the highest energy efficiency level by 2030, and innovative technological solutions are required to achieve this ambitious goal. This paper proposes a novel solar exoskeleton for the energy and architectural retrofitting of existing buildings, called En-Solex. The system, which consists of an external steel frame that wraps around buildings like a double skin, combines passive solar gain control (shading and greening) with high-efficiency active solar systems (PV panels) optimised for integration into existing building facades. The energy-saving potential of the system with different façade configurations is evaluated on a multi-family residential building located in a Mediterranean climate. The dynamic energy simulations show that the proposed solution can reduce the energy demand for space heating and cooling by 33.4% and 25.5% respectively. The En-Solex system integration combined with generator replacement results in a maximum heating and cooling reduction equal to 80.7% and 59.6% respectively. The surplus of electricity generated, thanks to the integration of RES, can lead to a net plus target, with the building exceeding its average annual electricity demand.

Life Cycle Analysis of a Renovation Project for Old Housing in Tashkent to Reduce Greenhouse Gas Emissions

The shift towards economic decarbonization through the reduction of carbon dioxide emissions has led to a focus on renovating and modernizing the existing buildings rather than constructing new ones. This research emphasizes the critical differences between the construction of new buildings and the modernization of the existing structures, specifically in the context of Uzbekistan. The country lacks a comprehensive methodology for accounting for the embodied carbon of building materials used in modernization projects. This research aims to bridge this gap by conducting a life cycle analysis (LCA) of a project focused on enhancing the thermal performance of the enclosing structures of a three to five-story multifamily residential building, commonly referred to as “Khrushchevka”. The analysis found that retrofitting buildings reduced greenhouse gas emissions by 13.5% through improved energy efficiency, despite the increase in initial emissions associated with the production and installation of insulation materials. The total reduction in carbon emissions over the entire life cycle of the reconstructed building was 24% (or 43.2 tons of CO₂), including emissions associated with the production of insulation. The payback period for emissions, which offsets the initial emissions during reconstruction, is 17 years.

Sustainability qualification tool for Italian multi-family buildings

Sustainability qualification tool for Italian multi-family buildings

Energy and economic simulation of a renewable energy community applied to a new generation ultra-low temperature district heating and cooling network

The work describes the energy and economic simulation of a renewable energy community with a social purpose applied to a residential and commercial new district in Milan, the eight buildings of which are connected to a new generation low temperature district heating and cooling network. The system is designed considering two substations for each building, each one providing heating and cooling load profiles by means of heat pumps, and an energy centre that exploits groundwater to extract and dissipate compensating heat at low temperature. Some roof mounted photovoltaic panels, owned by the district residents, cover the electricity needs resulting from the net metering of the renewable energy community. The members of the energy communities are in fact the multifamily buildings of the district acting as prosumers and some fragile families from the surroundings as simple consumers. The economic profits, represented by the subsidies coming from the diffuse self-consumed shared energy and from sold overproduced electricity, are distributed among the members to guarantee, first of all, an economic help against energy poverty to fragile families, and, secondly, a short pay-back-time for photovoltaics. Therefore, the operational strategy of the district network is optimized to maximize the shared electricity and the relative economic benefit by shifting, when possible, the electricity demand when the solar production is available. Finally, three different profit distribution mechanisms are analysed. The added value of this work is the evaluation, by means of a specific case study analysis, of the feasibility of an electric energy community from an economic as well as a regulatory point of view under current legislation.

Solar photovoltaic/thermal (PVT) technology collectors and free cooling in ground source heat pump systems

Ground source heat pump (GSHP) systems offer a low carbon heating and cooling solution for the decarbonization of buildings. As global temperatures rise, the cooling requirements of buildings will grow, even in regions where cooling systems have been historically uncommon due to their colder climate, such as Sweden. The combination of free cooling (FC) with GSHPs seems like a natural way to meet the increasing cooling needs, since the heat extracted from the building during the summer months can be injected into the ground to potentially regenerate the borehole field and enhance heat pump performance. However, a technology that is generally integrated with GSHP systems for borehole regeneration are photovoltaic/thermal collectors. This study investigates the performance of a ground source heat pump system with free cooling for a multi-family building in Stockholm, Sweden, and the interference on the free cooling capabilities of the system when photovoltaic/thermal collectors are present. The results demonstrate that the integration of PVT and FC not only maintains the cooling supply but also enhances heat pump performance, all the while reducing borehole length and land area requirements.

Analysis of Smoke Control System Performance of High-Rise Multifamily Residential Buildings Using Transient Simulation

In Korea, the general floor plan structure of multifamily residential buildings is such that the vestibules of stairs and fire service-access elevators are typically used together. The lobby of the emergency elevator faces the vestibules of the fire service-access elevators. The smoke control system supplies air for pressurization, and the inlet air discharge device for the exhaust can be exempted from this system. In a 49-story multifamily residential buildings with this structure, the smoke control system is operated at an outside temperature of −10 ℃ and indoor temperature of 20 ℃, and the fire room door is open. The possibility of the vertical spread of smoke owing to changes in the open areas of windows and escape elevator doors was analyzed. When the windows are closed, the vertical spread of smoke through the emergency elevator shaft and staircase may occur under both upper and lower fire conditions of the neutral zone. In particular, the flow path through the emergency elevator door is the main vertical spread path in the case of a fire below the neutral zone.

Are local retail services an amenity or a nuisance?

Abstract We test whether local retail services are considered a nuisance or an amenity and how this distinction is capitalized into residential property values. Using a rich, micro-spatial dataset on property sales transactions and business activity in New York City, we estimate the impact of access to neighborhood retail services on residential sales prices. We construct two instruments to channel supply-side drivers of retail change and to address concerns of endogeneity between changes in retail activity and property values. Results show that retail services that are more frequently consumed and experiential, and are located in relatively more mixed-use neighborhoods are positively capitalized into property values. Residents also pay more to be closer to more diverse retail clusters, and relatively less to be closer to chains. This is true across smaller 1-to-4 family homes as well as larger condos/coops and multi-family rental buildings. The price effects from certain classifications of retail, like restaurants and personal services, are mixed depending on the kind of residential property and the local concentration of the retail. Therefore, the relative strength of the amenity or nuisance effect is very much conditioned on the type of service and the localized neighborhood context.

Energy and cost savings of cool coatings for multifamily buildings in U.S. climate zones

While cool coatings have recently received much attention for building applications, their impact on building energy consumption strongly depends upon climatic conditions. Herein we evaluate the energy, cost, carbon, and interior comfort impact of cool coatings applied to a residential multifamily building across 32 climate zones in the United States by applying advanced cool coating properties to established building energy models. The model not only considers promising cool coating properties based upon recent experiments but also an ideal cool coating. Our calculations show that the ideal cool coating can achieve annual cooling energy savings of up to 6.64 kWh/m2 (Phoenix, AZ), annual net utility cost savings up to $1.16/m2 (Brawley, CA), and net annual carbon emission savings up to 7.7 % (Phoenix, AZ). We also estimate the change in interior temperature for buildings without space cooling systems and show that cool coatings make buildings in the warmest climate zones in the U.S. without space cooling more comfortable by 30 % to 50 % on a cooling degree days basis. Using analysis of variance, we examine the statistical relationships between building performance metrics and climatic parameters. The presented methodology enables evaluation of cool coating application to buildings in various climate zones across the world.

Utilizing weather forecast meteorological models for building energy simulations: A case study of a multi-unit residential complex

This study provides a detailed analysis of insulation materials’ impact on energy efficiency and environmental sustainability in a multifamily building. It extends its findings to anticipate future challenges in 2050, offering practical insights for building performance and climate adaptation. Key findings include the influence of changing external temperatures on heating and cooling energy needs. The study identifies mineral wool as the optimal choice for heating and expanded polystyrene for cooling ιn accordance with the highest standards, the best insulation is to be selected. Importantly, the research highlights the need to select insulation materials that align with evolving climate conditions and emphasizes the importance of adapting buildings and HVAC systems to reduce energy consumption. Furthermore, the study underscores the multifamily building’s commitment to reducing carbon dioxide equivalent (CO2e) emissions, demonstrating its dedication to sustainable practices. In summary, this analysis provides a scientifically grounded roadmap for architects, engineers, and policymakers to enhance energy efficiency and environmental sustainability in building design, insulation material selection, and climate adaptation.

Quantitative Analysis of Household Food Waste Collection in Warsaw: Assessing Efficiency and Waste Minimization

Food waste management is one of the key challenges of the circular economy and climate transition policies. The proper collection of food waste is the starting point for its further value recovery. Most of the quantitative and qualitative data used to measure the scale of food waste in households and its collection are based on statistical data, diaries, and questionnaires. There is a visible gap in research in terms of the use of direct research methods. This paper presents the results of a quantitative research study on household food waste accumulation and collection in Warsaw from two sources: single-family and multi-family households. The results of the study indicate that in Warsaw households, one can expect generation at the level of 33.4 kg·capita−1·year−1 of avoidable food waste and 38.2 kg·capita−1·year−1 of unavoidable food waste. The average food waste collection rate from households in Warsaw was determined to be at a level of 19.6 kg·capita−1·year−1. In multi-family buildings, which are dominant in Warsaw, this rate is half as pronounced (17.3 kg·capita−1·year−1) compared to single-family buildings (36.2 kg·capita−1·year−1). The average food waste collection efficiency rate from Warsaw households was at a level of 32%. Avoidable food waste accounted for 47% of all food waste generated. The study indicates a growing need to develop policy tools to support the separate collection and prevention of food waste.

Material intensity and embodied CO2 benchmark for reinforced concrete structures in Brazil

Cement and steel production significantly contribute to global CO2 emissions, with reinforced concrete structures accounting for a substantial portion. Therefore, optimizing the structural design helps reduce material and carbon intensity. However, industry-based benchmarks for material and carbon intensity of structures are scarce and lack transparency. This study fills this gap by analyzing detailed industry data derived from construction designs of 53 reinforced concrete structures for multifamily residential buildings in Brazil and assessing their cradle-to-gate material intensity and embodied CO2 emissions. The findings revealed significant variations in the usage of steel (70–159 kg/m³) and concrete (0.17–0.29 m³/m2). The quantity of structural materials ranged from 418 to 731 kg/m2, and the embodied CO2 ranged from 35 to 140 kg CO2/m2, including the variability in CO2 emissions during material production. Building height is the primary geometric parameter that determined material intensity and embodied CO2, particularly for columns. However, structural materials quantity varies considerably among buildings with the same number of stories, suggesting the presence of additional design parameters influencing material intensity. The results emphasize the role of designers in promoting decarbonization through dematerialization. Also, selecting the right material supplier is important as, on average, differences between manufacturers corresponds to a difference of 38 kg CO2/m2 in structural embodied CO2. Selecting low-carbon material suppliers and employing structural design benchmarking practices can efficiently reduce the embodied carbon of reinforced concrete structures.

The Role of Neighbourly Relations and Cooperation in Residents’ Willingness to Renovate Multi-Family Buildings in Croatia

The inadequate legislation on multi-family housing management in Central and Eastern European post-socialist countries calls for the exploration of additional determinants of building renovation on the level of the community of residents in a building. To this end, we present here an analytical framework called the mediated-Renovation Decision (m-RD) model for simultaneously testing the direct and indirect effects that neighbourly relations, cooperation of the co-owners’ representative with the co-owners, and acceptance of the building co-ownership concept have on co-owners’ willingness to invest in building renovation. The model is based on assessments made by 325 co-owners’ representatives from multi-family buildings in Croatia. The results show that the quality of neighbourly relations affects the co-owner’s willingness to renovate not directly, but indirectly through the level of their acceptance of the building co-ownership concept. The other indirect effect of neighbourly relations – through the level of the representative’s cooperation with co-owners – was not significant. The demonstrated analytical value of the m-RD model advocates for more complex studies of the role of neighbourly relations in collective decision-making and actions in the housing domain.

Performances of low frequency impact sound in wooden buildings

Since 1999 Sweden has required an extended frequency range for sound insulation in residential buildings, using 50 Hz as the lower limit. This regulation update has driven the design and development of multi storey residential building systems with wooden structures in a positive direction. Already in the mid 1980'ies there existed scientific proof that it the perceived impact sound will improve if the frequency range was extended below the lower standard limit 100 Hz at that time. Lately, researchers have indicated that the perceived impact sound can be even further improved if the frequency range is extended below current lower standardized limit of 50 Hz. Assume that the frequency range for impact sound requirement will be further extended to include frequencies from 25 Hz, what would that mean for modern wooden apartment buildings? Acouwood and Kuster & Partner AG are collecting data from 20 Hz, no matter if the standard measurement procedure cannot be applied below 50 Hz. It gives a good overview of potential annoyance risk but also of acoustic performances of modern sustainable multifamily buildings and how they can be improved. This paper summarizes measurement results of impact sound from 20 Hz in several wooden buildings.