Emerging Technologies In Building Energy Efficiency

The U.S. building stock are under continuous aging and deterioration with deferred maintenance that hinders their operation. Existing buildings account for more than 86% of the annual construction cost in the U.S. and often suffer from lack of acceptable level of thermal comfort, indoor air quality (IAQ) as well as high energy use and costs. Considering future energy constraints (e.g. global warming and energy resources) and cost (e.g. capital cost and operational cost) suggest a need for a paradigm shift in our current understanding of energy efficiency and indoor environmental quality (IEQ) of the older existing building stock. Major technological advances beyond our current knowledge are much needed to design energy efficient buildings and retrofit large numbers of buildings at scale. Our technologies advances should be converged on high performance building enclosure materials, advanced building controls, intelligent building mechanical systems, efficient building lighting fixtures, and smart building plug-load management. For example, currently, majority of the residential buildings and a significant number of commercial buildings in the U.S. do not have any building automation systems, suggesting an emerging need to develop low-cost building automation systems specifically for residential buildings. This presentation covers a wide range of much needed technological advances on different building components and systems in order to design energy efficient buildings or retrofit large numbers of buildings. The aim of this presentation is not only to provide opportunities to reduce energy consumption in older existing buildings but also to shed light on new solutions to harvest energy through buildings

Numerical Evaluation of the Local Weather Data Impacts on Cooling Energy Use of Buildings in an Urban Area

AbstractAccurate weather data plays an important role in the evaluation of building energy consumption in urban areas. The local air temperature and local wind speed can vary significantly due to the influence of microclimate conditions, while those parameters have a significant effect on energy demand especially in the summer. This study provides a new coupled numerical approach that building energy simulation (BES), using the airport weather data, transfers building surface temperature data to computational fluid dynamics (CFD) as the boundary conditions. In addition, the outdoor thermal environment is simulated using the CFD method and local weather data is calibrated and transferred to BES as the real-time meteorological data. A daily coupled simulation is performed for a building located in a specified urban density accounting for actual wind speed and direction. The comparison shows that the difference for daily building energy consumption is up to 2.5% using the airport weather data and local weather data. Therefore, accurate estimation of local weather data is necessary when on-site measured data is not available

Experimental Evaluations of the Impact of an Additive Oxidizing Electronic Air Cleaner on Particles and Gases

Electronic air cleaning (EAC) technologies have garnered significant attention for use in buildings. Many EAC technologies rely on the addition of reactive constituents to indoor air to react with gas-phase compounds, enhance particle deposition, and/or inactivate microorganisms. However, limited data are available on the efficacy of many EAC technologies and their potential to form chemical byproducts during operation. Here we experimentally evaluate the indoor air quality impacts, specifically targeting particles and gases but not microbial constituents, of a commercially available additive oxidizing EAC that generates positive and negative ions and hydrogen peroxide (H2O2). Tests were conducted in a large unoccupied test chamber in Chicago, IL and an unoccupied laboratory in Portland, OR under a combination of natural conditions (i.e., without pollutant injection) and perturbation conditions (i.e., with pollutant injection and decay). A combination of integrated and time-resolved measurements was used across both test locations. Chamber tests at lower airflow rates demonstrated that operation of the EAC: (i) had no discernible impact on particle concentrations or particle loss rates, with estimated clean air delivery rates (CADRs) for various particle measures less than ±10 m3/h, (ii) was associated with apparent decreases in some volatile organic compounds (VOCs) and increases in other VOCs and aldehydes, especially acetaldehyde, although a combination of high propagated uncertainty, limitations in test methods (e.g., lack of replicates), and variability between repeated tests limit what quantitative conclusions can be drawn regarding gas-phase organics; (iii) did generate H2O2, assessed using a crude measure, and (iv) did not generate ozone (O3). Laboratory tests at higher airflow rates, which involved injection and decay of particles and a single VOC (limonene), both simultaneously and separately, demonstrated that: (i) pollutant loss rates for both particles and limonene were slightly lower with the EAC on compared to off, yielding slightly negative pollutant removal efficiencies (albeit largely within propagated uncertainty) and (ii) there was a change in observed concentrations of one potential limonene degradation product, m/z 59 (putatively identified as acetone), with steady-state levels increasing from 10 ppb (air cleaner off) to 15 ppb (air cleaner on). No increases or decreases beyond measurement uncertainty were observed for other analyzed gaseous limonene degradation products. Overall, both chamber and laboratory tests demonstrated negligible effectiveness of this device at the test conditions described herein for removing particles and mixed results for VOCs, including decreases in some VOCs, no discernible differences in other VOCs, and apparent increases in other compounds, especially lower molecular weight aldehydes including acetaldehyde

A radiative cooling structural material.

Reducing human reliance on energy-inefficient cooling methods such as air conditioning would have a large impact on the global energy landscape. By a process of complete delignification and densification of wood, we developed a structural material with a mechanical strength of 404.3 megapascals, more than eight times that of natural wood. The cellulose nanofibers in our engineered material backscatter solar radiation and emit strongly in mid-infrared wavelengths, resulting in continuous subambient cooling during both day and night. We model the potential impact of our cooling wood and find energy savings between 20 and 60%, which is most pronounced in hot and dry climates

Performance assessment of a membrane liquid desiccant dehumidification cooling system based on experimental investigations

A membrane-based liquid desiccant dehumidification cooling system is studied in this paper for energy efficient air conditioning with independent temperature and humidity controls. The system mainly consists of a dehumidifier, a regenerator, an evaporative cooler and an air-to-air heat exchanger. Its feasibility in the hot and humid region is assessed with calcium chloride solution, and the influences of operating variables on the dehumidifier, regenerator, evaporative cooler and overall system performances are investigated through experimental work. The experimental results indicate that the inlet air condition greatly affects the dehumidification and regeneration performances. The system regeneration temperature should be controlled appropriately for a high energy efficiency based on the operative solution concentration ratio. It is worth noting that the solution concentration ratio plays a considerable role in the system performance. The higher the solution concentration ratio, the better the dehumidification performance. However simultaneously more thermal input power is required for the solution regeneration, and a crystallization risk in the normal operating temperature range should be noted as well. The system mass balance between the dehumidifier and regenerator is crucial for the system steady operation. Under the investigated steady operating condition, the supply air temperature of 20.4°C and system COP of 0.70 are achieved at a solution concentration ratio of 36%

Solar pond powered liquid desiccant evaporative cooling

Liquid desiccant cooling systems (LDCS) are energy efficient means of providing cooling, especially when powered by low-grade thermal sources. In this paper, the underlying principles of operation of desiccant cooling systems are examined, and the main components (dehumidifier, evaporative cooler and regenerator) of the LDCS are reviewed. The evaporative cooler can take the form of direct, indirect or semi-indirect. Relative to the direct type, the indirect type is generally less effective. Nonetheless, a certain variant of the indirect type - namely dew-point evaporative cooler - is found to be the most effective amongst all. The dehumidifier and the regenerator can be of the same type of equipment: packed tower and falling film are popular choices, especially when fitted with an internal heat exchanger. The energy requirement of the regenerator can be supplied from solar thermal collectors, of which a solar pond is an interesting option especially when a large scale or storage capability is desired

Reinforcement Learning for Building Management Systems

It is increasingly common to design buildings with advanced sensing and control systems to improve energy efficiency, indoor air quality which impacts health and productivity. However, there has been limited progress in making building automation systems “intelligent,” as the performance of such buildings is often limited by reactive control systems, primarily using setpoint limits and fixed operation schedules. The complex nature of building control problems motivates the application of state-of-the-art software engineering methods and techniques. Agent-based models (ABM) are well-suited for controlling complex engineering systems such as those employed in building heating, ventilation, and air-conditioning (HVAC) systems. In this paradigm, a collection of interacting autonomous components (i.e., agents) adapt and make decisions in changing environments. There is a growing body of literature on adaptive agents in ABMs in many industries, but few have looked at the compatibility of ABMs with artificial intelligence (AI) optimization approaches. In most cases, conventional optimization techniques, such as mixed integer linear programming and gradient descent, have been used to find an optimal solution. This paper explores the use of an actor-critic, model-free algorithm based on a deterministic policy gradient that provides continuous control to generate the desired supply air temperature. The case study develops a thermal energy storage (TES) agent that determines the optimal valve position to manage the temperature of the cooling water flow. The case study was developed using the Intelligent Building Agents Laboratory at the National Institute of Standards and Technology. Future work will use multiple agents (i.e., air handling unit, TES, chiller) acting in cooperation or competition

Simulation of pollution dispersion behind a building using a RANS-LES model

Today the air pollution is one of the biggest problem specially in mega cities and it effects directly on human health and environment. in this article pollution dispersion for the light gas pollutant around a building in turbulent 3D incompressible flow using a hybrid turbulence model has been investigated. Pollution around a building in low speed wind may aggregate in some regions and make special problems for pedestrian and environment. Turbulent wind flow over buildings due to the complexity like sharp corners, ground effect, different vortexes and other factors is one of the best choices to evaluate efficiency and accuracy of turbulence methods. DES is hybrid RANS-LES models for simulating turbulent flow which for their characteristic, treat near wall as RANS and farther the wall act as LES model. Consequently computational time will decrease compared to traditional LES models. To evaluate DES model, DES results has been compared with smagorinsky and one-equation model. Also to validate, the simulation results are compared with experimental data. The DES results show good agreement with experiment and LES models and this hybrid model has a good potential for large scale wind engineering problems

Experimental dataset on adsorption of Arsenic from aqueous solution using Chitosan extracted from shrimp waste; optimization by response surface methodology with central composite design

The aim of data was to evaluate the efficiency of chitosan extracted from shrimp waste for Arsenic adsorption and optimization by response surface methodology (RSM) with central composite design (CCD). The data showed that, with increasing contact time, the amount of adsorption increased and the optimal contact time was about 60 min. With increasing pH decreased adsorption, although this reduction was not significant. The optimum pH was obtained at 4.41. The average amount of adsorbent capacity was also about 1.3 mg/g. Overall, chitosan extracted from shrimp waste could be considered as an efficient material for the adsorption of Arsenic from aqueous solution. Keywords: Chitosan, Arsenic, Aqueous solution, Adsorptio

Dataset on comparing the corrosion indices of alum and ferric chloride coagulants with phosphate dose elevation

The aim of this data was to assess and compare the corrosion indices of alum and ferric chloride coagulants in conventional coagulation process of water with elevation of phosphate dose. After preparing synthetic water samples, jar experiments were performed with elevation of different phosphate doses using alum and ferric chloride coagulants. Then, corrosion indices of Ryznar and Langelier of water samples were calculated. The results indicated that the values of Ryznar and Langelier index in the experimental samples were 7 and less than zero, and the water conditions were under saturated. The corrosion and precipitation indices indicated that the water samples can be considered as corrosive waters. Keywords: Corrosion indices, Alum and ferric chloride coagulants, Wate