Square Meter Of Floor Area Research Articles

Driving net zero: Comprehensive evaluation of whole life carbon in domestic hot water systems

Low-temperature domestic hot water (DHW) systems provide significant carbon reduction benefits, supporting the UK’s 2050 net-zero target. Typically, low water volume applications do not need recirculation and storage when instantaneous heaters are employed, such applications can be more flexible in terms of temperature range and safety requirements. However, commercial applications may have high volumes of hot water and hence, will require high working temperatures to satisfy the recirculation requirements. This study developed a comprehensive toolkit to benchmark the embodied and operational carbon in terms of kgCO2e/m2 for various DHW systems, including equipment, refrigerants, and operational emissions. Analysis of seven DHW designs for an office building revealed that low-temperature systems consistently demonstrate the lowest whole-life carbon (WLC), underscoring the impact of grid decarbonisation and low-GWP refrigerants. The WLC results are normalised per square metre of floor area. Low-temperature systems showed the lowest WLC even with the inclusion of water treatment and chemical dosing systems.

Evaluating whole life carbon impact of climate control systems in net-zero building designs

This paper proposes a methodology for the early-stage selection of climate control systems in building design, focusing primarily on minimising whole life carbon (WLC) emissions. A significant obstacle is the limited availability of comprehensive data on the carbon footprint of Heating, Ventilating and Air Conditioning (HVAC) equipment and materials, along with the challenges or absence of early-stage energy models and detailed HVAC designs. This paper presents and compares the WLC for seven different HVAC systems and designs for an office building. The study demonstrates how HVAC engineers and designers can make informed decisions by selecting HVAC systems, materials, and components in the early stages. It illustrates the outcomes of a typical project design from both WLC and operational energy perspectives. Additionally, the paper provides normalised WLC benchmarks for each system in terms of kgCO2e per square metre of floor area.

Referentna vrijednost za novu drvenu zgradu s gotovo nultom potrošnjom energije u Europi

To mitigate dangerous climate change, a drastic reduction of CO2 emissions is needed by 2030. Buildings contribute significantly to emissions, with the use phase of existing buildings being responsible for the majority of energy consumption. In addition, environmental problems associated with the production of raw materials, construction, and the end of life of buildings are serious concerns that require urgent solutions. Life cycle assessment (LCA) and the EU-recommended Environmental Footprint (EF) are widely accepted tools to measure environmental impacts throughout a product life cycle. However, assessing the environmental performance of wooden buildings remains a challenge. This study presents a benchmark for an average new European wooden building fulfilling the European nearly Zero Energy Building (nZEB) requirement. The benchmark utilizes the recommended EU EF impact categories with normalization and weighting, allowing for easy and quick comparisons. The results communicate the average environmental impact per square meter of floor area over one year. This benchmark is a suitable comparison point for new wooden building designs and is used as an effective tool for architects and designers during the initial planning stages of wooden buildings. By using this benchmark, the environmental performance of the building can be improved, and the communication and interpretation of LCA results can be facilitated for customers and other relevant stakeholders.

Do housing rental and sales markets incentivise energy-efficient retrofitting of western Germany’s post-war apartments? Challenges for property owners, tenants, and policymakers

A post-World War 2 building boom in western Germany (the original Bundesrepublik) produced a cohort of some 8 million apartments, built in 1946–1979, that are relatively homogeneous in design and materials. On average, these apartments are very energy-inefficient, consuming around 147 kWh of heating energy per square meter of floor area per year (kWh/m2/y). Retrofitting them to about 50 kWh/m2/y is necessary to meet Germany’s climate goals. Considerable skill and infrastructure have developed to attempt to achieve this, but it is expensive. This study investigates whether sales and rental markets disincentivise property owners from retrofitting these apartments to high energy efficiency standards. Data from sales and rental advertisements in 2019–2021 in Germany’s largest online housing advertisement portal, Immoscout24, were used to estimate market sales and rental premiums for energy efficiency in these apartments. For property owners who retrofit apartments then sell them, sales premiums for energy efficiency generally fail to compensate for the retrofit costs, unless the renovation is subsidised. Meanwhile, for purchasers, the reduction in energy costs due to higher energy efficiency does not compensate for the higher purchase price. Likewise, for landlords/landladies who retrofit apartments then rent them out, the rental premiums due to higher energy efficiency are nowhere near sufficient to compensate for the retrofit costs. Tenants, however, can often offset the rental premium through energy savings. In all four cases, there is regional variation. Based on a detailed investigation of this market for energy efficiency, this study suggests specific policy interventions to compensate for these market anomalies.

Embodied Carbon and Construction Cost Differences between Hong Kong and Melbourne Buildings

Limiting the amount of embodied carbon in buildings can help minimize the damaging impacts of global warming through lower upstream emission of CO2. This study empirically investigates the embodied carbon footprint of new-build and refurbished buildings in both Hong Kong and Melbourne to determine the embodied carbon profile and its relationship to both embodied energy and construction cost. The Hong Kong findings suggest that mean embodied carbon for refurbished buildings is 33-39% lower than new-build projects, and the cost for refurbished buildings is 22-50% lower than new-build projects (per square metre of floor area). The Melbourne findings, however, suggest that mean embodied carbon for refurbished buildings is 4% lower than new-build projects, and the cost for refurbished buildings is 24% higher than new-build projects (per square metre of floor area). Embodied carbon ranges from 645-1,059 kgCO2e/m2 for new-build and 294-655 kgCO2e/m2 for refurbished projects in Hong Kong, and 1,138-1,705 kgCO2e/m2 for new-build and 900-1,681 kgCO2e/m2 for refurbished projects in Melbourne. The reasons behind these locational discrepancies are explored and critiqued. Overall, a very strong linear relationship between embodied energy and construction cost in both cities was found and can be used to predict the former, given the latter.

Hybrid Input-Output Analysis of Embodied Carbon and Construction Cost Differences between New-Build and Refurbished Projects

Refurbishing buildings helps reduce waste, and limiting the amount of embodied carbon in buildings helps minimize the damaging impacts of climate change through lower CO2 emissions. The analysis of embodied carbon is based on the concept of life cycle assessment (LCA). LCA is a systematic tool to evaluate the environmental impacts of a product, technology, or service through all stages of its life cycle. This study investigates the embodied carbon footprint of both new-build and refurbished buildings to determine the embodied carbon profile and its relationship to both embodied energy and construction cost. It recognizes that changes in the fuel mix for electricity generation play an important role in embodied carbon impacts in different countries. The empirical findings for Hong Kong suggest that mean embodied carbon for refurbished buildings is 33–39% lower than new-build projects, and the cost for refurbished buildings is 22–50% lower than new-build projects (per square meter of floor area). Embodied carbon ranges from 645–1059 kgCO2e/m2 for new-build and 294–655 kgCO2e/m2 for refurbished projects, which is in keeping with other studies outside Hong Kong. However, values of embodied carbon and cost for refurbished projects in this study have a higher coefficient of variation than their new-build counterparts. It is argued that it is preferable to estimate embodied energy and then convert to embodied carbon (rather than estimate embodied carbon directly), as carbon is both time and location specific. A very strong linear relationship is also observed between embodied energy and construction cost that can be used to predict the former, given the latter. This study provides a framework whereby comparisons can be made between new-build and refurbished projects on the basis of embodied carbon and related construction cost differentials into the future, helping to make informed decisions about which strategy to pursue.

Estimation of Carbon Dioxide Emissions Generated by Building and Traffic in Taichung City

The emissions of carbon dioxide generated by urban traffic is generally reflected by urban size. In order to discuss the traffic volume generated in developed buildings and road crossings in a single urban block, with the metropolitan area in Taichung, Taiwan as an example, this study calculates the mutual relationship between the carbon dioxide generated by the traffic volume and building development scale, in order to research energy consumption and relevance. In this research, the entire-day traffic volume of an important road crossing is subject to statistical analysis to obtain the prediction formula of total passenger car units in the main road crossing within 24 h. Then, the total CO2 emissions generated by the traffic volume in the entire year is calculated according to the investigation data of peak traffic hours within 16 blocks and the influential factors of the development scale of 95 buildings are counted. Finally, this research found that there is a passenger car unit of 4.72 generated in each square meter of land in the urban block every day, 0.99 in each square meter of floor area in the building and the average annual total CO2 emissions of each passenger car unit is 41.4 kgCO2/yr. In addition, the basic information of an integrated road system and traffic volume is used to present a readable urban traffic hot map, which can calculate a distribution map of passenger car units within one day in Taichung. This research unit can be used to forecast the development scale of various buildings in future urban blocks, in order to provide an effective approach to estimate the carbon dioxide generated by the traffic volume.

Establishing environmental benchmarks to determine the environmental performance of elementary school buildings using LCA

Benchmarks are required to determine the environmental performance of new buildings. Through LCA, this study assessed the environmental impacts of 23 elementary school buildings in South Korea. By conducting statistical analysis (Pearson correlation analysis, partial correlation analysis, and Mann-Whitney test), gross floor area, latitude, and longitude were influence factors which cause the differences in environmental impacts among buildings. The differences in environmental impacts by gross floor area can be considered by defining the functional unit as one square meter of floor area. The differences in environmental impacts by region can be considered after dividing 23 elementary school buildings according to latitude and longitude. Based on the results of the two-step cluster analysis and the Mann-Whitney test on latitude and longitude, the environmental impacts of 23 elementary school buildings were divided into two clusters, with the exception of human carcinogenic potential and human non-carcinogenic potential. Therefore, this study presented the benchmarks in two clusters. For instance, the benchmarks for global warming potential in Clusters One and Two were 3.70E+03 and 2.53E+03 kg-CO2 eq./m2, respectively. The benchmark for the human carcinogenic potential was 8.63E−08 casescan/m2. The benchmarks are expected to be used in determining the environmental performance of new elementary school buildings.

Evaluating extended land consumption in building life cycle to improve land conservation: A case study in Shenyang, China

This paper aims to evaluate land consumption caused by materials flow in building life cycle for feasible land conservation measures in China. As distinct from the land occupied by buildings, extended land consumption was defined as lands consumed during raw material extraction and construction waste disposal. And corresponding statistical model, including two computing formulas for single building and a statistical method for regional buildings was designed. Using the proportions of weights from raw materials to building materials and the ratios between raw material weights and destroyed land areas, extended land consumptions at construction stage and demolition stage by per square meter of floor area were calculated as target parameters respectively for three common building structures: brick-concrete, frame and steel structure. Based on building structures, predicted time of demolition and reconstruction, and the target parameters, extended land consumption from all buildings of Shenyang City from 2014 to 2064 in four situations were calculated and compared. The results illustrate that extended land consumption accounts for 1.78% of the whole city area and 29.18% of occupied land, and could be reduced by 80% by improving construction quality for longer serviceable building life and adopting prefabricated construction for greater recycling ratios of scrap building materials. Material flow caused land consumption provides an extended dimension to the concepts on land consumption; the statistical model provides a framework to quantify the relationships between building patterns and land consumption. Our approach permits more accurate land consumption prediction for decision-making in sustainable land utilization.

The monitored performance of four social houses certified to the Code for Sustainable Homes Level 5

This paper presents the energy and water use of 4 social houses certified to the Code for Sustainable Homes Level 5 in Gainsborough, UK. The houses were monitored over 2 years, from July 2012 to September 2014. As the houses have the same construction and energy efficiency characteristics, the study offered a unique opportunity to investigate the effects of occupant behaviour on the dwellings performance. Electricity, gas and water consumptions were measured through data logging and meter readings. Surveys and interviews were conducted throughout to gain insights into tenants understanding and interactions with low energy features in their homes. Significant differences were observed in the amount of energy and water used. The annual space heating consumptions differentiated by a factor of 2.2per square metre of floor area. Hot water heating demands varied by a factor of 3.5per square metre of floor area or by 2.5per person per year. Mains water consumptions varied by a factor of 2.2litres per person per day in 2013.

APPLICATION OF THE EXPONENTIAL GREY MODEL ON THE MAINTENANCE COST PREDICTION FOR A LARGE SCALE HOSPITAL / EKSPONENTINIO PILKOJO MODELIO TAIKYMAS PROGNOZUOJANT DIDELĖS LIGONINĖS EKSPLOATACINES SĄNAUDAS

Realizing the maintenance cost distribution and predicting the future tendency are important for facility managers to efficiently arrange the limited budget. This paper collects 16,228 maintenance records of a representative hospital in Taiwan and further analyzes the cost distribution. Besides, by calculating the maintenance cost of per square meter of floor area per year (dollar/m2/year) and comparing with the previous studies, this paper also points out the relationship between maintenance cost and the operation ages. moreover, this paper establishes a hybrid grey model termed as EGM(1,1), which adopting exponential series to identify the residual error series resulted from grey model, to predict the maintenance cost. The repair cost of hospital building from 1998 to 2006 is adopted to demonstrate the applicability and practicability of EGM(1,1). Results show that the proposed model can predict the tendency precisely. Santrauka Norint efektyviai išdėstyti ribotą biudžetą, pastatų ūkio valdytojai turi suprasti eksploatacijos sąnaudų pasiskirstymą ir sudaryti ateities tendencijų prognozes. Šiame darbe surinkti 16 228 įrašai apie reprezentacinės Taivano ligoninės eksploataciją ir jais remiantis analizuojamas sąnaudų pasiskirstymas. Apskaičiavus metines eksploatacijos sąnaudas vienam kvadratiniam metrui (doleriai/m2/metus) ir palyginus jas su ankstesniais tyrimais, darbe taip pat parodomas ryšys tarp eksploatacijos sąnaudų ir objekto amžiaus. Be to, darbe sudaromas hibridinis pilkasis modelis, pavadintas EGM(1,1), kuriame naudojant eksponentines eilutes nustatomos liktinės paklaidų eilutės, gautos pilkajame modelyje, taip siekiant prognozuoti eksploatacines sąnaudas. Naudojant 1998–2006 m. ligoninės pastato remontui išleistą sumą pristatomas EGM(1,1) taikymas ir praktiškumas. Rezultatai rodo, kad pasiūlytas modelis tendencijas gali prognozuoti tiksliai.

Benchmarking operation and maintenance costs of French healthcare facilities

PurposeThe purpose of this paper is to present a benchmarking study of operation and maintenance costs of French healthcare facilities between 2008 and 2009. The investigation presents findings using quantitative methods, including cumulative frequency and descriptive statistics. The purpose also is to highlight and capture the performance profile of long‐term hospitals, using several operational cost drivers.Design/methodology/approachA literature review revealed that there are no studies on the benchmarking of operation or maintenance costs of health facilities in France. Operational cost drivers reported in literature from other countries were used as the underlying constructs for this research, with a view to generating a benchmarking framework for the health assets in the data sample. The data were extracted from the databases of the hospitals concerned. Some of the data were collected via interviews and questionnaires. Statistical analysis was carried out to investigate and generate potential benchmarking cost curves. Potential operational cost drivers were extracted and used to develop cumulative frequency curves for benchmarking purposes.FindingsThe authors found that cost per bed ratio can be used as an efficient metric to classify health facilities into similar to data sets. The results also show that the operational costs of utilities, maintenance and operations & maintenance staff correlate positively and significantly with the square meter of floor area. This relationship indicates that 82 per cent of the operational performance can be explained by this linear relationship. However, it was found that the relationship between the total of operational costs per square meter with the floor is negatively correlated and surprisingly only explains 41 per cent of the performance of the health asset operational cost variation in the data sample.Originality/valueThe paper presents the first metric benchmarking method in France which allows health facility managers in France to evaluate and develop operational strategies, with a view to reducing the costs burden.

Thermal upgrades of existing homes in Germany: The building code, subsidies, and economic efficiency

One of the cheapest ways to reduce CO 2 emissions is thermal renovation of existing homes. Germany is a world leader in this project, with a strict building code, generous state subsidies, and an advanced renovation infrastructure. The effects of its policies are here explored in the light of progressive tightening of the building code, and the strict criteria for subsidies. Data on costs and outcomes of residential building renovations are presented from published reports on renovation projects, and cross-checked with projects investigated directly. Comparisons are made in terms of euros invested for every kilowatt hour of heating energy saved over the lifetime of the renovations, for standards ranging from 150 kWh (the lowest standard) to 15 kWh (the highest) of primary energy use per square metre of floor area per year. It is found that the lowest standard is an order of magnitude more cost-effective than the highest, in terms of both energy saved per euro invested, and return on investment over the lifetime of the renovations, regardless of fuel prices. It is argued that this throws into question Germany's policy of progressively regulating for higher renovation standards, and offering subsidies only for projects that go beyond the minimum standard.

Characterization of minienvironments in a cleanroom: Assessing energy performance and its implications

Filtered fans in cleanrooms can demand up to 400 W or more electric power per square meter of floor area to rapidly supply, recirculate, and exhaust air. “Minienvironments” that control particle concentrations within enclosures may not only maintain a level of stringent cleanliness, but also offer opportunities in energy savings and reducing operation costs through integration with adjacent cleanrooms. In order to better understand the total performance of minienvironments in operation, this paper characterizes energy performance of five different minienvironments (designated as ISO-Cleanliness-Class-3) that were in operation and were housed in a traditional, larger ISO-Cleanliness-Class-4 cleanroom used in the microelectronic industry. The measured parameters in the field investigation included electric power demand, airflows, in addition to physical characteristics and cleanliness performance of the minienvironments. In this paper, measured energy performance and associated metrics are compared to those of cleanrooms of various cleanliness classes. This paper develops new understanding of energy performance of minienvironments and quantifies the magnitudes of potential energy savings that could result from integrating minienvironments in traditional cleanrooms while achieving effective contamination control. Based upon this study, achieving energy savings by a magnitude of up to 60–86% was possible in the cleanroom facility housing the minienvironments. The paper also suggests means of increasing energy savings in minienvironments applications, including optimal design and operation, and space management in clean spaces.

Free cooling of a building using PCM heat storage integrated into the ventilation system

This article presents a study of the free cooling of a low-energy building using a latent-heat thermal energy storage (LHTES) device integrated into a mechanical ventilation system. The cylindrical LHTES device was filled with spheres of encapsulated RT20 paraffin, a phase-change material (PCM). A numerical model of the LHTES was developed to identify the parameters that have an influence on the LHTES’s thermal response, to determine the optimum phase-change temperature and to form the LHTES’s temperature-response function. The last of these defines the LHTES’s outlet-air temperature for a periodic variation of the inlet ambient-air temperature and the defined operating conditions. The temperature-response function was then integrated into the TRNSYS building thermal response model. Numerical simulations showed that a PCM with a melting temperature between 20 and 22 °C is the most suitable for free cooling in the case of a continental climate. The analyses of the temperatures in a low-energy building showed that free cooling with an LHTES is an effective cooling technique. Suitable thermal comfort conditions in the presented case-study building could be achieved using an LHTES with 6.4 kg of PCM per square metre of floor area.

Duct systems in large commercial buildings: physical characterization, air leakage, and heat conduction gains

Through field studies in large commercial buildings and reviews of building plans, we investigated the effective leakage areas (ELAs), air-leakage rates, and conduction heat gains of duct systems. Different methods for measuring air-leakage rates were also compared. ELAs of supply ducts ranged from 0.4 to 2.0 cm 2 per square meter of floor area served, and from 1.0 to 4.8 cm 2 per square meter of duct surface area. On a per-unit-floor-area basis, these duct ELAs are comparable to the values measured in residences. The corresponding values of duct leakage class were 60 to 270, much higher than the range of 3 to 12 reported by ASHRAE [ASHRAE Standard 111-1988, Practices for Measurement, Testing, Adjusting, and Balancing of Building Heating, Ventilation, Air Conditioning, and Refrigeration Systems, American Society of Heating, Refrigerating, and Air Conditioning Engineers, Atlanta, 1988] as attainable for quality duct construction and sealing practices when leakage at connections to duct-mounted equipment is not considered. The measured air-leakage rates as a percentage of the inlet air flow rate varied from 0% to 30%, with most of the measurements falling between 10% and 20%. Large inconsistencies among the air-leakage rates determined from different measurement procedures exemplify the need for further development and evaluation of measurement methods. Heat gains between the outlet of the cooling coils and the supply registers caused supply air temperatures to increase, on average, by 0.6°C to 2°C. The corresponding values of conduction effectiveness were 0.75 to 0.90; thus, heat conduction decreased the cooling capacity of the supply air exiting registers by 10% to 25%. Because these results are based on studies in only a few buildings, generalizations from these findings are premature.

Integrating energy consciousness in the design process

The design process for an intelligent, energy conscious building which was built, along with the design tools that were applied, is presented. The building, situated in the hot–humid climate of Rehovot, Israel, houses the laboratories and offices of the Weizmann Institute's Environmental Science and Energy Research Department. Alternative bio-climatic design options were proposed and evaluated throughout the detailed design stage. A building energy performance index (BEPI) was established for each alternative. This index reflects the total amount of energy consumption for heating, cooling, ventilating and lighting used per square meter of floor area. Thermal modeling for the different design alternatives were carried out by means of an hourly dynamic simulation model. The model solves simultaneously the heat transfer equations through all exterior walls, taking into account the thermal mass of each external wall as well as internal partitions. The model was extended to include hourly calculations of daylighting and geometrical shading coefficient of the windows, as well as automated and `smart' control strategies.

Pre‐bid building price forecasting accuracy: price intensity theory

A theory of pre‐bid building price forecasting accuracy is proposed, based on the heuristic bias framework and with reference to the common practice of basing building price forecasts on the price per square metre of floor area, termed here as Price Intensity (PI). The main prediction of the theory, that high PI contracts will be underestimated and low PI contracts will be overestimated, is tested by a re‐analysis of a set of Singapore data and in comparison with previous work.

Computer aided energy conscious building design

The design process for an energy conscious building, which was built, along with the computer aided design tools that were applied, is presented. The building, situated in the hot-humid climate of Rehovot - Israel, houses the laboratories and offices of the Weizmann Institute's Environmental Science and Energy Research Department. Alternative bio-climatic design options were proposed and evaluated throughout the detailed design stage. A building energy performance index (BEPI) was established for each alternative. This index reflects the total amount of energy consumption for heating, cooling, ventilating and lighting used, per square meter of floor area. Thermal modeling for the different design alternatives were carried out by means of an hourly dynamic simulation model ENERGY. The design strategies were determined by the model PASYS, the shading devices were designed and evaluated using SUNSHADES and SHADING design tools. The building is monitored for the last whole year, and the measured values are close to the predictions.

Energy performance of occupied non-domestic buildings: Assessment by analysing end-use energy consumptions

Significantly improved understanding of the energy performance of an existing building can be achieved by investigating the energy consumption for individual end uses (heating, lighting, ventilation etc.) and comparing these consumptions per square metre of floor area with yardstick values for each end use. A method is presented for apportioning metered electricity consumption into end uses, generally without the need for extensive monitoring. Techniques are described for using the results to assess the building in terms of design and performance indices, and presenting the results for building management or research uses.