Retrofit Projects Research Articles

Multifamily energy-efficiency retrofit programs: a Florida case study

Multifamily buildings are an important target for efficiency improvements because of their energy savings potential and housing market share. Yet few multifamily retrofit projects have been completed in hot-humid regions and even fewer studies have measured and verified savings from such projects. Addressing this gap, the purpose of our research is to assess the impacts of energy-efficiency upgrades to multifamily buildings in Orlando, FL. Specifically, we measure the first-year electricity savings from retrofits to 232 units in four apartment complexes. Annual savings per unit averaged 2094 kWh (22 %) and ranged from 1700 kWh (18 %) to 3811 kWh (29 %) across complexes. Monthly savings ranged from 48 kWh (9.4 %) in December to 340 kWh (31 %) in August. From these core findings, we estimate that tenants in treatment units saved an average of $272 on their electric bills. We also find evidence to support a strategy of targeting upgrades to improve overall savings and program cost-effectiveness. Results are being used to guide development of a utility demand-side management program for multifamily property owners. Progress in this market requires additional pilot projects, access to utility data, reliable measurement and verification of savings, and innovative financing structures.

Assessing the impacts of preferential procurement on low-carbon building

The significance of global warming is shaping building procurement, with much of the effort aimed at reducing greenhouse gas emissions through a preferential bidding mechanism. However, only a limited number of studies have quantitatively estimated the potential impact of bid preference on the emission reduction from building construction. The aim of this paper is to improve our understanding of how bid discounts change owners' procurement costs and the magnitudes of emission mitigation. A two-stage optimization model is designed to help the owner determine the discount rate that would automatically control the emission of the awarded contract within a desired level. The goal is for bidders to regard emission reduction efforts as an investment, with returns coming in the form of an increased chance of winning the bid. Our results imply that for the building retrofit project studied herein, a discount rate of 0.6 is suggested for every percentage of emission reduction. This discount level reduces greenhouse gas emissions by 28.2% while raising procurement costs by 3.7% relative to a non-preference mechanism. The increased procurement costs can be partially compensated under existing cap-and-trade scheme. The results show that the choice of discount significantly alters bidders' efforts on emission mitigation, and emission control cost can be minimized with the proposed optimization algorithm.

Low potential heat utilization of bromine plant via integration on process and Total Site levels

In this paper, the energy efficiency of bromine production site is analysed and pathways for heating and cooling demands reduction are proposed. Detailed inspection of the process stream system and heat integration on process and site levels was performed. The enterprise capacity is 25 t/d of sodium bromide crystals and 27 t/d of liquid bromine, the concentration of bromine ion in the raw material is 0.8–1 g/L. The PA (Pinch Analysis) and TSA (Total Site Assessment) were used for estimation of energy saving potential and design of retrofit project. Heat recovery on site level is performed by intermediate utility applying Total Site Profiles. Structure of heat recovery system and minimal temperature difference are determined. It is shown that the process with improved heat integration consumes 57% of hot and 97% of cold utilities required by existing production site.

The development of a monolithic aerogel glazed window for an energy retrofitting project

Abstract The implementation of innovative materials for energy saving is a main focus in the building sector. In this context, aerogels are often indicated as really promising materials. In particular, aerogel blankets have already shown potential in many retrofitting projects while the development of glazing systems with aerogel is still at the research stage. This paper describes the development of double pane glazing systems with monolithic silica aerogel in their cavity. The results of a multi-disciplinary analysis, including thermal and lighting tests, are reported. This new monolithic aerogel window is then used in the retrofitting project of an educational building completed in the 1960s. A level 3 energy audit was conducted through measurements of the envelope transmissibility, the building air-tightness, and several indoor environmental parameters. The energy audit provided data for an accurate energy model and to perform a detailed analysis of the energy consumptions of the building. Several energy saving measures for the case study building were then investigated. Lighting and energy simulations allowed comparisons of different designs of the aerogel window with the intent to guarantee sufficient daylight, clear perception of the external environment, and high energy saving. Finally, this paper provides a sensitivity analysis of the investigated retrofitting strategies in different climates, with the intent to show where aerogel windows may represent a valuable retrofitting choice.

Simulating Performance Risk for Lighting Retrofit Decisions

In building retrofit projects, dynamic simulations are performed to simulate building performance. Uncertainty may negatively affect model calibration and predicted lighting energy savings, which increases the chance of default on performance-based contracts. Therefore, the aim of this paper is to develop a simulation-based method that can analyze lighting performance risk in lighting retrofit decisions. The model uses a surrogate model, which is constructed by adaptively selecting sample points and generating approximation surfaces with fast computing time. The surrogate model is a replacement of the computation intensive process. A statistical method is developed to generate extreme weather profile based on the 20-year historical weather data. A stochastic occupancy model was created using actual occupancy data to generate realistic occupancy patterns. Energy usage of lighting, and heating, ventilation, and air conditioning (HVAC) is simulated using EnergyPlus. The method can evaluate the influence of different risk factors (e.g., variation of luminaire input wattage, varying weather conditions) on lighting and HVAC energy consumption and lighting electricity demand. Probability distributions are generated to quantify the risk values. A case study was conducted to demonstrate and validate the methods. The surrogate model is a good solution for quantifying the risk factors and probability distribution of the building performance.

Telling tales: using stories to remake energy policy

To benefit and protect the populace, government policies often promise aspirational changes to current practice. Different kinds of narratives are important in the framing, explanation, motivation, and understanding of policies and strategies. For example, the UK government's 2008 Climate Change Act proclaimed that all new homes will be zero carbon by 2016. This ‘hero story’, where society is ‘saved’ by clever technologies, is inspiring, positive and familiar. An alternative is the ‘learning story’, where things are not quite as simple as they first seemed. In a learning story, protagonists are normal people who need to overcome a challenge. In energy policy, the learning story could address the gap between the technical potential and what is achieved in practice. Three real-world examples from retrofit and new-build projects are used to show how implicit narratives can create conflict when the tellers (e.g. researchers) have to tell one kind of story but have data for the other. Recommendations are provided for a balanced approach to the deployment of different kinds of tales by policy-makers, researchers, implementers and users. Harnessing the learning story and developing a ‘caring story’ could motivate policy-makers and the public to invest effort in building performance.

Process modification of Total Site Heat Integration profile for capital cost reduction

The Total Site Profile (TSP) can be a powerful tool to evaluate the potential for further Heat Integration improvement for a Total Site (TS). A systematic Total Site Heat Integration (TSHI) methodology to target decreasing the capital cost of heat transfer units at Total Sites has been developed. The methodology includes a set heuristics that have been developed to identify and prioritise the strategic process changes to apply, as a result of changes in the TSP shape. The TSP and expanded Total Site Problem Table Algorithm (TS-PTA) can provide useful insights for the plant designers to identify “where”, in terms of which temperature interval, and which streams within the entire TS to focus the process modification efforts. The keep hot stream hot (KHSH) and keep cold stream cold (KCSC) principles can be applied to favourably change the TSP shape to provide a larger temperature driving force to further reduce the HTA and capital costs. In one of the case study, the application of KHSH and KCSC on TSP increases the temperature driving force between the medium pressure steam utility and process resulting in a reduction of 3,827 m2 heat transfer area (HTA) and a saving of 10% in heat exchangers cost. The proposed changes to the selected streams should be assessed from feasibility, practicality and economic perspectives. The selected and potentially acceptable process modification options can be conveniently merged with potential retrofit project (e.g. to increase plant capacity) considered for the Total Site.

Retrofit of heat-integrated crude oil distillation columns

Engineering projects to increase the capacity of existing heat-integrated crude oil distillation columns are commonplace. Retrofit projects aim to exploit the processing capacity of existing units by changing operating parameters and/or modifying equipment. Operational modifications can be effective and usually incur little capital expenditure, but equipment changes may also be needed to achieve retrofit objectives. Existing retrofit methodologies for crude oil distillation systems mainly focus on increasing heat recovery, increasing crude oil throughput and/or increasing the yield of most valuable products by optimising column operating parameters. However, methodologies that also consider hardware modifications are lacking. The present work proposes a systematic retrofit methodology based on distillation column and heat exchanger network (HEN) simulation. Hydraulic correlations are used to consider replacing existing distillation column internals with high-capacity trays and/or structured packings. Industrially relevant case studies illustrate the benefits of the proposed methodology to analyse and assess hardware modifications for the retrofit of distillation systems when increasing capacity.

Risks in Energy Performance Contracting (EPC) projects

Compared with conventional energy retrofit projects, Energy Performance Contracting (EPC) projects present a different risk picture to the contracting parties as its primary focus is to deliver promised energy savings to building owners (hosts). This study aims to identify the key risks inherent in EPC projects, and investigate the hosts’ concerns on the use of EPC, as well as propose practical measures to enhance the wider adoption of EPC. Two separate questionnaire surveys were conducted with respondents comprising ESCOs (n=34) and hosts (n=168) in Hong Kong. Results indicate that the key risks to ESCOs are possible payment default of hosts after installation, uncertainty of baseline measurement, and increase in installation costs in EPC projects. For hosts, their primary concerns in considering the use of EPC include possible long payback periods, project complexities and repayment ability. In addition, the respondents agree with three practical measures to enhance the adoption of EPC in future, including the promotion of successful projects, modification of government procurement practices, and government's backup of loans. The findings of this study provide useful pointers to key stakeholders of EPC projects for harnessing their risk perceptions and mitigating their concerns on this procurement approach.

Optimal maintenance planning for sustainable energy efficiency lighting retrofit projects by a control system approach

The energy savings achieved by implementing energy efficiency (EE) lighting retrofit projects are sometimes not sustainable and vanish rapidly given that lamp population decays as time goes by if without proper maintenance activities. Scope of maintenance activities refers to replacements of failed lamps due to nonrepairable lamp burnouts. Full replacements of all the failed lamps during each maintenance interval contribute to a tight project budget due to the expense for the lamp failure inspections, as well as the procurement and installation of new lamps. Since neither “no maintenance” nor “full maintenance” is preferable to the EE lighting project developers (PDs), we propose to design an optimal maintenance plan that optimises the number of replacements of the failed lamps, such that the EE lighting project achieves sustainable performance in terms of energy savings whereas the PDs obtain their maximum benefits in the sense of cost–benefit ratio. This optimal maintenance planning (OMP) problem is aptly formulated as an optimal control problem under control system framework, and solved by a model predictive control (MPC) approach. An optimal maintenance plan for an EE lighting retrofit project is designed as a case study to illustrate the effectiveness of the proposed control system approach.

Comparisons of inverse modeling approaches for predicting building energy performance

In building retrofit projects, retrofit savings can be estimated by comparing building energy use before and after installing Energy Conservation Measures (ECMs). A complicating factor is that there is no direct measurement of the reduced energy use that is solely attributable to the retrofit. Indeed, simple comparisons by subtracting the post-retrofit energy use from the pre-retrofit would ignore the impact of other factors, such as weather and occupancy with constantly changing patterns, on the total building energy use. Data-driven models (i.e., derived by inverse modeling approaches) that are trained with monitored pre-retrofit building data can be used as the baseline models in a retrofit project. However, to be effective, the baseline energy models must be capable of singling out the impact of ECMs and ignoring the influence of other factors. A commonly used method to achieve this goal is to develop a statistical model that correlates energy use with weather and other independent variables.This paper first reviews four mainstream baseline data-driven energy models used to characterize building energy performance: change-point regression model, Gaussian process regression model, Gaussian Mixture Regression Model, and Artificial Neural Network model, These models are then applied to an office building to predict the Heating, Ventilation, and Air-Conditioning (HVAC) hot water energy consumption. Several model accuracy measures such as R2, RMSE, CV-RMSE, and sensitivity to sample frequency, and reliability, are evaluated and compared.

West Virginia has not directed sufficient resources to treat acid mine drainage effectively

Acid mine drainage from abandoned coal mines continues to cause major problems in the State of West Virginia (in the United States), and groups of local residents are attempting to improve water quality by managing passive treatment systems. The challenges faced by these groups in obtaining effective treatment system performance are illustrated by experiences of one such group: Friends of the Cheat. As a result of pollution from abandoned coal mines, the lower Cheat River watershed is seriously degraded. West Virginia is failing watershed groups because it provides them with capital costs to initiate and manage treatment of acid mine drainage but does not provide funds for operation and maintenance activities needed for effective treatment. To compensate for the absence of funding to address routine maintenance issues, Friends of the Cheat and other groups apply for government grants to fund retrofits projects, which themselves are not supplied with operating funds. The result is a cycle of ineffective treatment and inefficient use of resources. If West Virginia is going to rely on community-based watershed groups to clean up pollution problems from abandoned coal mines, it should provide them with the resources they need to be successful.

Sustainable building energy efficiency retrofit for hotel buildings using EPC mechanism in China: analytic Network Process (ANP) approach

Building Energy Efficiency Retrofit (BEER) is considered as a valuable way to improve energy efficiency of high-energy-consumption buildings. Sustainable BEER helps integrate sustainable development strategy into existing buildings and retrofit projects. To ensure BEER projects that can fulfill the sustainable development strategy, Energy Performance Contracting (EPC) is one possible market mechanism to deliver energy efficiency projects. Sustainable BEER under the EPC mechanism is a comprehensive system which involves the various demands of sustainable dimensions, performance criteria and groups of project success factors, making multi-criteria decisions become a challenging problem for decision makers. This paper aims to examine the interrelationships of sustainable BEER by focusing on an existing hotel building. EPC mechanism is applied in the case study and an effective Analytic Network Process (ANP) approach is also employed in the research. The result indicates that sustainable BEER in hotel buildings under the EPC mechanism is mainly determined by project control mechanism, available technology, organizing capacity of the team leader, trust, accurate Measurement and Verification (M&V), and team workers' technical skills. Decision makers should dedicate more attention to these aspects. From the research findings, several policy implications are proposed in this paper.

Evaluation of Lighting Performance Risk Using Surrogate Model and EnergyPlus

In building retrofit projects, numerous sources of uncertainty about building performance need to be addressed. Deterministic simulations are usually used to estimate the potential performance difference from a baseline building. This approach needs building model calibration. Varying uncertain building parameters could lead to orders of magnitude simulation times. For example, in a lighting retrofit project, uncertainty (e.g., lamp input wattage, and varying weather conditions may negatively affect model calibration and lighting energy savings, which increases the chance of default on performance contract. Therefore, the aim of this paper is to develop a method that can conduct risk analysis based on building model (e.g., building information modelling). A stochastic occupancy model is used to simulate the occupancy pattern. Two lighting control strategies (occupancy and daylight controls) and two luminaire types (LED and fluorescent) are considered. Historical weather data is analyzed using statistical analysis, and the extreme weather conditions are generated to evaluate the impact of weather conditions on the lighting and HVAC energy usage. Then, EnergyPlus is used to simulate the energy usage based on different lamp types, control strategies, occupancy patterns, and weather conditions. A surrogate model is developed by using a small sample size of simulation data to construct an approximation surface to enable fast computing time. This method can evaluate impact of uncertainty of risk factors (e.g., occupancy level, luminaire type, weather) on lighting and HVAC energy usage and lighting electricity demand. This method can also prioritize risk factors based on sensitivity analysis on building performance and help users to choose different lamp types to minimize risks.

Regenerative Design of Existing Buildings for Net-Zero Energy Use

This paper explores feasibility of achieving net-zero energy goals in retrofitting commercial buildings. An existing commercial building in Holyoke, Massachusetts was chosen as the research target to study how to integrate passive design strategies and energy-efficient building systems to improve the building performance and reduce energy consumption. Also, the objective was to investigate how to maximize energy savings and reach net zero energy goals by utilizing renewable energy sources for building's energy needs. Based on extensive energy modeling and simulations, multiple design considerations were investigated, such as material selection, improvements to building envelope, retrofitting of HVAC and lighting systems, occupancy loads, as well as application of renewable energy sources. The comparative analysis of simulation results was used to determine how specific techniques lead to energy saving and cost reductions. The research results show that this commercial building is able to meet net-zero energy use after appropriate design manipulations and use of renewable energy sources. The strategies and methodologies can be applied to other adaptive reuse and retrofit projects, and improve energy performance of existing buildings.

Prediction of instantaneous exhaust particulate concentrations

Gaseous emissions usually are available on a continuous basis from diesel vehicle emissions testing, but particulate matter (PM) emissions are usually only available as a single mass number over a test cycle. Continuous PM emissions are valuable for conformity and hot-spot analyses to support roadway project design and to determine the engine-out PM for after treatment retrofit projects. For diesel vehicles without particulate filters one may argue that carbon monoxide and hydrocarbon emissions may be correlated with the elemental carbon and organic carbon fractions in their exhaust. Methodologies for predicting instantaneous PM production rate from heavy-duty diesel vehicles were developed. These methodologies used combinations of instantaneous and idle carbon monoxide and hydrocarbon production rates with integrated PM production to predict instantaneous PM production rates for each specific vehicle. Comparison of results produced by these methodologies with measured PM productions rates is presented. Apportioning total PM mass over a period of vehicle activity using gaseous emissions is shown to be reliable.

Integrating Life Cycle Assessment with Green Building and Product Rating Systems: North American Perspective

The development of green building rating systems (GBRS) and sustainability metrics for buildings, including building products, is reviewed from a North American perspective. The Leadership in Energy and Environmental Design (LEED) system and the Living Building Challenge (LBC) are highlighted as primary examples of different levels of GBRS. Life cycle assessment (LCA) is introduced as a preferred method of quantifying sustainability, and its integration into current GBRS is examined a prominent building example. Two example applications of LCA to building products associated with GBRS – carpet and roof membranes – are provided. In the first example, conventional carpet was compared with carpet meeting the standards of the LBC's materials exclusion criteria (Red List, via the Declare product labeling system). In the second example, LCA was applied to both the manufacture and use phases of roof membrane alternatives for a building retrofit project, one of which would have aided in achieving LEED certification. The Declare-listed products did not perform better in every LCA impact category, and the GBRS-preferred roof system performed more poorly in all LCA impact categories, while suggesting the need for additional LCA categories. Both examples help to illustrate the complexity and tradeoffs encountered while integrating the quantitative perspective of LCA and the qualitative perspective of GBRS.

Experimental Study on a Novel Optimal Differential Pressure Reset Method for Online Application in Chilled Water System

This paper firstly define most unfavorable thermodynamic loop to reflect the dynamic situation of terminal cooling load distribution, then present its online identification method that can easily applied for optimal reset of differential pressure. We use the optimal domain of maximum valve position among whole braches in chilled water system to calculate the variation of differential pressure setpoint, and control the pumps according to the optimal setpoint. We applied presented method to a VWF retrofit project in a Suzhou factory building and evaluate its energy saving effect through its equipped building energy management system. Experimental results showed that presented method can achieve 22%-53% pump power consumption savings compared to traditional control method. During the test period, the average level of valve position of presented method was highest among all tested control strategies. The optimal reset method of differential pressure presented in this paper is an energy efficient, high stability and easily online applied control method.

Zero 2020, the Low Energy Retrofit and Renovation of a Precast Concrete Building in Ireland Exploring site nZEB Energy Retrofit in Precast Grid Optimized Low Rise ‘60s Buildings

Zero 2020, the Low Energy Retrofit and Renovation of a Precast Concrete Building in Ireland Exploring site nZEB Energy Retrofit in Precast Grid Optimized Low Rise ‘60s Buildings Marc O Riain, Dr. Jim Harrison, Dr Kevin McCarthney Abstract This paper contextualizes the 1967 design of Regional Technical College (RTC) campuses in Ireland, with reference to the influence of oil crises on early green design and the establishment of a regulatory environment. Variation between NZEB and Passive House low energy strategies are discussed. Design Science and Action research inform solution-oriented methodologies in a pilot retrofit project on 1.5% area of an RTC building. Problem investigation notes previous schemes, stakeholder’s goals, building evaluation and energy performance diagnosis. Environment interaction between context and artifact are discussed. Design validation includes simulated envelope performances, which inform design iterations. Phenomena are evaluated in terms of energy performance during a critical time window. Findings from the design process of the pilot project are presented, outlining its limitations, scalability and commercialization potential. Full Text: PDF DOI: 10.15640/jea.v3n1a15

Cost Minimisation for Total Site Heat Recovery

In this paper minimisation of total cost for retrofit of Total Site heat recovery system is proposed. It based on analysis of balanced Total Site Profiles and includes procedure for calculation of heat transfer area. Heat transfer area is calculated for different regions with use of intermediate utility and direct heating and cooling. Minimal temperature difference between Total Site Profiles is analysed. Global minimum of heat transfer area for Total Site recovery is calculated for array of minimal temperature differences. It is analysed with utility consumption, numbers of units and material of equipment. Selection of minimum total cost for retrofit project of site recovery system is proposed.