Large Office Building Research Articles

Performance assessment of hybrid chiller systems for combined cooling, heating and power production

Hybrid chiller systems that combine electric and absorption chillers can play critical roles in performances of a combined cooling, heating, and power (CCHP) or trigeneration system. The objective of the present study is to investigate a new strategy for hybrid chiller-based CCHP systems that can optimize electric power production while achieving zero-excess electricity generation for a given building. Using this operation strategy, energy and environmental performances were examined for two U.S. Department of Energy reference buildings (large office and hospital) located in two climates (San Francisco, CA and Long Island, NY). The results show that the hybrid chiller-based CCHP systems can save the primary energy consumption up to 5.8 GWh/y for the large office building and 13.6 GWh/y for the hospital compared to the conventional reference system that utilizes a central grid. More significant energy savings are realized for the hospital than the large office mainly due to high electric and thermal loads throughout the year. Carbon dioxide emission associated with a CCHP system highly varies with the emission factor of a local grid. In case of using the hybrid chiller system in Long Island, NY, the carbon dioxide emission is 0.2–1.5 kton/y lower than the reference system, whereas it is 1.1–1.5 kton/y higher in San Francisco. However, compared to traditional CCHP systems that utilize only absorption chillers, the hybrid chiller-based CCHP systems can reduce carbon dioxide emission by 0.7 kton/y for the large office and 3.5 kton/y for the hospital. When comparing the effects of building types and local climates, building types have more significant effects on the energy performance, while local grid conditions have larger impacts on carbon dioxide emission of a hybrid chiller-based CCHP system. Overall, the study results suggest that the hybrid chiller-based CCHP systems can reduce more energy and carbon dioxide emission for commercial buildings or districts with high thermal and electric loads during the cooling season.

Estimation of power analysis in WLAN infrastructure

Design of indoor WLAN infrastructure requires prediction of radio waves propagation inside the building, which can be a complex problem. Therefore some sort of planning is required before the wireless networking hardware is set up.The goal of this work is to provide an estimate of the received power within a building. Physical environment is a large office building, of which we consider one part. The building is constructed of various materials. In this paper, we present a model that simulates the considered problem. Received power is calculated and compared to receiver minimum input level sensitivity given by the IEEE 802.11 Standards. Numerical results were obtained using MATLAB.

Analysis of Heating and Cooling Loads of Electrochromic Glazing in High-Rise Residential Buildings in South Korea

This study compares the impact of the recently developed electrochromic glazing technology on load reduction by comparing it with the double-glazing and shading devices that are sold commercially for high-rise residential buildings in Korea. These buildings are similar to large office buildings in terms of their high window-to-wall ratio. The energy consumption of such buildings was simulated using an analytical model of a high-rise residential building. The patterns between the heating and cooling loads were found to be similar to that of office buildings, in that the cooling load was considerably higher than the heating load. This study hypothesizes that the load reduction performance of electrochromic glazing with variable solar control and high solar radiation rejection is superior to that of existing double-glazing products and shading devices. This hypothesis was tested by analyzing the cooling and heating loads of buildings with different types of double glazings. Bleached electrochromic glazing exhibited lower transmittance than colored glass double glazing, low-e double glazing, and double glazing with a shading device, and is thus not effective in reducing heating load. Colored electrochromic glazing provided higher solar radiation rejection than colored glass double glazing and low-e double glazing, and thus is effective in reducing cooling load.

Modelling and analysis of unsolicited temperature setpoint change requests in office buildings

This paper presents an analysis conducted upon custom temperature setpoint change request data collected from four large office buildings. In three of these buildings, the setpoint changes were executed upon hot and cold complaints; and in the fourth building, the occupants could adjust their setpoints through their thermostats. Using concurrent indoor and outdoor temperature records, multivariate logistic regression models predicting the frequency of custom setpoint change requests were developed. The indoor temperatures that minimize the frequency of thermal complaints or thermostat overrides were determined with these models. It is argued that these temperatures can be used to select building specific default seasonal temperature setpoints. The results indicate that the majority of the setpoint change requests were either to increase the default 22 °C temperature setpoints during the cooling season or to decrease them during the heating season. Custom setpoint change requests were registered 24 times more frequently when occupants were permitted to make temporary thermostat overrides. It was also identified that the operators tend to make greater setpoint changes upon hot and cold complaints than the occupants make through their thermostat overrides.

A techno-economic feasibility analysis of hybrid renewable energy supply options for a grid-connected large office building in southeastern part of France

This study gives emphasis to the techno-economic analysis of renovating the energy supply system of a grid-connected large office building through a Hybrid Renewable Energy System (HRES). The study is focused on how to minimize electricity consumption from the grid by producing as much as possible renewable energy, and in addition to that it also observes the economic impacts of integrating green vehicles, such as hydrogen cars, electric cars etc. which are indispensable elements of a sustainable city, in the proposed system. The work initiated collecting the sites monthly electrical load data, climate data and associated monetary data with the aim of investigating a renewable energy supply system feasibility study. Three alternative scenarios are developed according to the project needs and these scenarios are modelled by a hybrid renewable energy system design tool. The study concludes with a direct comparison of the economic feasibility, renewable energy fraction, and emissions among all systems, looking for the more appropriate and sustainable solution. It is found that integrating solar photovoltaic (PV) curtails more than 43% electricity consumption of the office building from the utility grid. The result also shows that per unit cost of electricity of PV/Grid system to satisfy the load demand is around 10% lower compared to the utility grid tariff and furthermore, it minimizes over 90% emission compared to the total emission in the study site. This study will provide helpful insights to the relevant stakeholders and policy makers in the development of grid connected HRES system.

Changes in respiratory and non-respiratory symptoms in occupants of a large office building over a period of moisture damage remediation attempts.

There is limited information on the natural history of building occupants’ health in relation to attempts to remediate moisture damage. We examined changes in respiratory and non-respiratory symptoms in 1,175 office building occupants over seven years with multiple remediation attempts. During each of four surveys, we categorized participants using a severity score: 0 = asymptomatic; 1 = mild, symptomatic in the last 12 months, but not frequently in the last 4 weeks; 2 = severe, symptomatic at least once weekly in the last 4 weeks. Building-related symptoms were defined as improving away from the building. We used random intercept models adjusted for demographics, smoking, building tenure, and microbial exposures to estimate temporal changes in the odds of building-related symptoms or severity scores independent of the effect of microbial exposures. Trend analyses of combined mild/severe symptoms showed no changes in the odds of respiratory symptoms but significant improvement in non-respiratory symptoms over time. Separate analyses showed increases in the odds of severe respiratory symptoms (odds ratio/year = 1.15‒1.16, p-values<0.05) and severity scores (0.02/year, p-values<0.05) for wheezing and shortness of breath on exertion, due to worsening of participants in the mild symptom group. For non-respiratory symptoms, we found no changes in the odds of severe symptoms but improvement in severity scores (-0.04‒-0.01/year, p-values<0.05) and the odds for mild fever and chills, excessive fatigue, headache, and throat symptoms (0.65–0.79/year, p-values<0.05). Our study suggests that after the onset of respiratory and severe non-respiratory symptoms associated with dampness/mold, remediation efforts might not be effective in improving occupants’ health.

Value impacts of energy efficiency retrofits on commercial office buildings in Toronto, Canada

This study strengthens the business case for building energy efficiency retrofits in Canada by studying the relationship between building energy efficiency and value. This is accomplished through a detailed examination of four large Toronto commercial office building retrofit case studies using pre- and post-retrofit energy and financial data. To assess the change in asset value with retrofit improvements, the income capitalization approach to building appraisal is adopted. This model for provides a link between energy efficiency and value through net operating income. Due to the challenges of obtaining energy-use and financial data, the sample size is small. However, even though the data is limited, the analysis reveals that energy retrofitting buildings can decrease operating costs, increase occupancy rates, and increase effective rent (rental revenue), thereby increasing net operating income. Although these benefits may not necessarily be achieved in every retrofit, where these benefits are realized, positive effects on value result.

Development of Whole‐Building Energy Models for Detailed Energy Insights of a Large Office Building with Green Certification Rating in Singapore

AbstractDetailed insights on energy use are missing for the building stock in Singapore that may aid reduction of energy consumption through a targeted approach. Therefore, we created two whole‐building energy models for a large commercial office building in the tropics representing a fully glazed and a concrete façade. We used Singapore's current building codes, which include compliance with local green‐rating system, and collaboration between two entities with first‐hand experience with design, construction, and operation of buildings in the tropics to define the models. The models provide a first step towards a set of standardized inputs and assumptions for office buildings in the tropics. The results show an energy use intensity of 146 kWh m−2 a−1. The three highest energy consumers are air conditioning and mechanical ventilation (43 %), lighting (29 %), and plug loads (21 %) whereas the two main sources of cooling loads are ventilation (29 %) and conduction and radiation through windows (20 %). Finally, we evaluated the effects of exterior shading on the fully glazed energy model to demonstrate the use of the models to building stakeholders.

Study and analysis of office building energy consumption performance in severe cold and cold region, China

Large office building energy consumption in China is several times that of ordinary buildings. Therefore, it is necessary to study the characteristics of large office buildings to determine their e...

An energy performance evaluation methodology for individual office building with dynamic energy benchmarks using limited information

A rational and reliable energy benchmark is useful for understanding and enhancing building performance while most buildings cannot provide sufficient information for a detailed energy assessment. This work presents a systematic methodology of developing dynamic energy benchmarks for individual office building with very limited information. Simultaneously, an energy consumption rating (ECR) system is established to provide vertical energy assessment for individual office building in a short time span, i.e. hourly. Based on the data produced by DOE prototype large office building model performed in the EnergyPlus environment, this study is conducted in three steps: (1) Step 1: Data preparation; (2) Step 2: Development of the dynamic energy benchmarks; and (3) Step 3: Evaluation of the dynamic energy benchmarks and ECR system. Based on the decision tree analysis, the system energy consumption is classified into eight patterns by few commonly accessible weather and time variables, i.e. outdoor dry-bulb temperature, relative humidity, day type and time type. Then, four energy benchmarks are developed according to four energy consumption patterns on weekdays. To verify the effectiveness of the proposed dynamic energy benchmarks, it is used to evaluate the building energy performance on September, October and November, respectively. Besides, comparative analysis is conducted between the energy baseline (i.e. the same benchmark is used for all energy consumption patterns) and proposed dynamic energy benchmarks. Accordingly, the hourly ECRs were calculated using energy baseline and proposed dynamic energy benchmarks, respectively. Results showed that the energy baseline can be improved by using the proposed dynamic energy benchmarks. And the proposed method is capable of evaluating the energy performance of information poor office buildings.

Multicriteria evaluation of sustainable energy solutions for Colosseum

Colosseum is a large office building in the capital region of Finland. The building owner operates on the highly competitive office rental market. With increasing emphasis on environmental responsibility, energy efficiency and sustainable energy solutions can provide competitive edge on the rental market. This study evaluates in terms of multiple criteria different alternatives to enhance the energy solutions of the building. The alternatives included different configurations of solar power, ground source heat, and roof constructions, along with district heating. Decision criteria included internal rate of return, energy efficiency, CO2 emissions, and attractiveness. Attractiveness was evaluated by a set of experts in office building valuation. The alternatives were compared using Stochastic Multicriteria Acceptability Analysis (SMAA), which is a simulation based method for decision problems where different kinds of uncertain information are represented by probability distributions. As novelty, the pairwise winning indices were used to form a stochastic ranking of alternatives. Analyses were conducted both without and with decision maker’s preference information. Most preferred alternatives were based on ground source heat. However, these alternatives require extensive renovation to install a hydronic central heating system. If such renovation is considered infeasible, then solar power alternatives become most preferred.

DESIGN AND IMPLEMENTATION OF CONSTRUCTION MATERIAL MANAGEMENT SCHEME BASED ON RFID TECHNOLOGY

With the improvement of construction demand and the reduction of land price, the construction of all kinds of buildings has become the current development trend in addition to the need for housing. Whether it is a large commercial center, office or landmark building, its construction materials in addition to enhancing the performance, but also to build an automated and effective material management system. This paper studies the design and implementation of the construction material management scheme based on RFID technology, hoping to improve the management system and improve the management efficiency through the application of RFID technology.

Multi-objective optimal component sizing of a hybrid ICE + PV/T driven CCHP microgrid

This paper presents a multi-objective optimization approach in order to find the optimal capacities of a CCHP microgrid, to meet the power, heating and cooling loads of a large office building located in Tehran. The CCHP microgrid is modeled in two states: (a) an Internal Combustion Engine (ICE) driven system; (b) a solar assisted CCHP system including ICE and Photovoltaic/Thermal (PV/T) panels. The model is implemented in MATLAB and optimized via NSGA-II. The optimization is carried out to simultaneously minimize the Net Present Cost (NPC) and maximize the Primary Energy Saving (PES) of the system. Carbon Emission Reduction Ratio (CER) is also calculated to assess the environmental performance of the microgrid.The results revealed that, despite a slight increase in the average value of NPC, the CCHP system integrated with solar energy have a considerably better performance in energy saving and emissions than the ICE driven system.

대형 오피스빌딩의 부동산 자산관리서비스가 임차 구성원 만족도에 미치는 영향분석 - 그랑서울과 FKI타워를 중심으로

대형 오피스빌딩의 부동산 자산관리서비스가 임차 구성원 만족도에 미치는 영향분석 - 그랑서울과 FKI타워를 중심으로

Life cycle analysis of energy consumption and CO2 emissions from a typical large office building in Tianjin, China

Tiejian Tower, a large public building in Tianjin, China, is one of the many energy-efficient buildings the country has built to reduce energy consumption and carbon dioxide (CO2) emissions. Based on first-hand data from the project and using an ecological input–output table, the embodied energy and CO2 emissions for that building were estimated for its life cycle. Four scenarios were designed to assess the impacts of space heating and power mix, and sensitivity analysis was conducted to examine the major factors that can reduce CO2 emissions. The operational stage consumed more energy than any other stage, and contributed the most to CO2 emissions. The influence of energy-efficient equipment and their lifespan on energy consumption and CO2 emissions varied greatly. Policies that encourage construction of buildings with longer lifespans and promote energy-saving measures can reduce energy consumption and carbon emissions in the buildings sector. The state should also supervise the operation of large buildings, involve large public buildings in future emissions-trading systems, and consider the power mix while planning such buildings.

Diffusion des certifications environnementales sur le marché des bureaux franciliens

Cet article étudie la diffusion de la certification Hqe sur le marché des grandes surfaces de bureaux. Depuis son lancement en 2005, ce référentiel déclaratif s'est rapidement répandu parmi les immeubles neufs et restructurés de grande taille d'Ile-de-France. À partir de la littérature sur la diffusion des innovations et d'une base de données de transactions, les facteurs de l'offre (liés aux investisseurs et aux promoteurs) et de demande (liés aux entreprises utilisatrices de locaux) sont successivement analysés afin d'interpréter les mécanismes sous-jacents à cette rapide pénétration du marché. Enfin, les caractéristiques spatiales de cette diffusion sont étudiées. Les résultats suggèrent que la réorganisation de l'offre explique le décollage de la certification dans les quartiers d'affaires émergents. La systématisation de la prise à bail de locaux certifiés par de grandes sociétés cotées a joué un rôle plus tardif pour la diffusion dans les quartiers d'affaires traditionnels.

Development of a Office Price Index in Seoul Using Two Stage Estimation Methodology Developed by MIT/CRE

부동산 투자시장이 서울 오피스 투자를 중심으로 크게 성장하고 있다. 그럼에도 불구하고 투자 의사결정의 기준이 되는 가격지수는 개발이 미진했다. 부동산 가격지수 산출의 방법론이 잘 알려졌음에도 불구하고 가격지수 개발이 미진한 것은 충분한 거래사례를 확보하기 어렵기 때문이다. 지역이 특정 될수록 이 같은 문제는 심각해질 수 밖에 없다. 유사한 문제에 직면한 MIT/CRE는 이러한 문제를 해결하기 위해 2단계 추정법을 개발했다. MIT/CRE 2단계 추정법은 분기별 거래사례가 부족하다면 4개 분기의 사례를 합해 가격변동률을 구한 후 이를 다시 분기별로 환원해 분기별 가격지수를 도출하는 방식이다. 본 연구의 목적은 MIT/CRE 2단계 추정법을 활용해 서울 오피스 가격지수를 산출하는 것이다. 지수 산출에 활용된 실거래 자료는 일부 시점에서 반복매매쌍이 확보되지 못해 전통적인 반복매매모형을 적용하기 어려웠다. 그러나 MIT/CRE 2단계 추정법을 활용할 경우 모든 분석시점에 대해 반복매매쌍을 확보할 수 있게 되어 분기별 가격지수를 산출할 수 있었다. 추정된 가격지수는 4분기 통합 자료의 가격변동을 잘 반영하고 있어 실무적으로 활용이 가능할 것으로 기대된다. 본 연구는 MIT/CRE 2단계 추정법을 활용해 제한된 거래사례를 기반하더라도 충분히 안정적인 가격지수를 산출할 수 있다는 점을 입증했다는데 의의가 있다.There has been an increasing acceptance of the repeat sale index in commercial as well as residential real estae markets. However, with Seoul office building data, researchers have difficulty in producing the repeat sale index. Sales of large office buildings are infrequent, and thus forming a sales pair is not always possible, especially when a submarket price index is concerned. We introduce and apply the MIT/CRE two-stage method to overcome this problem. When quarterly data are not sufficiently large, the method pools four quarter data to produce a series of successive four-quarter price indices, and then decompose the series into quarterly indices. We confirm that the method can be applied on Seoul s office building sales data. MIT/CRE method can be a reliable alternative in producing stable office building price index.

An Analysis on NOI Determinants of Small and Medium Buildings

Most of academic research on office market has focused on large office buildings. Although compared to large office building, small and medium buildings have distinctive characteristics in location, tenant types, main use, owner types, and so on, there is little research on small and medium buildings. The purpose of this research is to analyze how small and medium building’s various features affect its Net Operating Income (NOI). For an empirical research, we collects real transaction data from 2009 to 2015 in Seoul and analyze these data by using multiple regression model. For a regression analysis, numerous features of the building have possibility to affect NOI, are categorized into trade area, location, site, building, tenant, management characteristics. The empirical research shows the NOIof small and medium building was affected by trade area, location, site, building, tenant, management characteristics. The regression analysis shows the trade area, location, and site characteristics such as proximity to main trade area, proximity to subway station, corner location, and zoning of site, have significant effects on NOIo f small and medium building. This study confirms building characteristics such as gross floor area, age of building, elevator installation, and proportion of leasable area to 1st floor gross area, have significant impacts on NOI. The NOI of small and medium building is also influenced by the tenant and management characteristics such as proportion of leasable area for commercial use to gross area, its vacancy rate, whether building is used for residential use or building owner, and its management fee charging system. Through this study, we can confirm the NOIof small and medium building is affected by different characteristics from large office building.

Spatial distribution of internal heat gains: A probabilistic representation and evaluation of its influence on cooling equipment sizing in large office buildings

Internal heat gains from occupants, lighting, and plug loads are significant components of the space cooling load in an office building. Internal heat gains vary with time and space. The spatial diversity is significant, even for spaces with the same function in the same building. The stochastic nature of internal heat gains makes determining the peak cooling load to size air-conditioning systems a challenge. The traditional conservative practice of considering the largest internal heat gain among spaces and applying safety factors overestimates the space cooling load, which leads to oversized air-conditioning equipment and chiller plants. In this study, a field investigation of several large office buildings in China led to the development of a new probabilistic approach that represents the spatial diversity of the design internal heat gain of each tenant as a probability distribution function. In a large office building, a central chiller plant serves all air handling units (AHUs), with each AHU serving one or more floors of the building. Therefore, the spatial diversity should be considered differently when the peak cooling loads to size the AHUs and chillers are calculated. The proposed approach considers two different levels of internal heat gains to calculate the peak cooling loads and size the AHUs and chillers in order to avoid oversizing, improve the overall operating efficiency, and thus reduce energy use.

Analysis of a combined heating and cooling system model under different operating strategies

The paper presents an analysis of a combined heating and cooling system model under different operating strategies. Cooling demand for air conditioning purposes has grown steadily in Poland since the early 1990s. The main clients are large office buildings and shopping malls in downtown locations. Increased demand for heat in the summer would mitigate a number of problems regarding District Heating System (DHS) operation at minimum power, affecting the average annual price of heat (in summertime the share of costs related to transport losses is a strong cost factor). In the paper, computer simulations were performed for different supply network water temperature, assuming as input, real changes in the parameters of the DHS (heat demand, flow rates, etc.). On the basis of calculations and taking into account investment costs of the Absorption Refrigeration System (ARS) and the Thermal Energy Storage (TES) system, an optimal capacity of the TES system was proposed to ensure smooth and efficient operation of the District Heating Plant (DHP). Application of ARS with the TES system in the DHS in question increases net profit by 19.4%, reducing the cooling price for consumers by 40%.