The Challenges of Monitoring Energy Consumption to Assess Behavioural Changes in Occupants During Renovation Projects from a Low Budget Point of View

This study presents the challenges of monitoring energy consumption to assess behavioral changes in occupants during renovation projects and how to develop a strategy to overcome those challenges. Three buildings containing seventeen flats in total were monitored during a period of over two years, monitoring energy consumption and internal temperature of the flats. The energy consumption for the flats was capture by the use of a Current Cost smart meter placed at the ground floor of each block of flats in a cover under stairs. Wireless sensors were clamped to each flat. The smart meters were not connected to the internet or a computer, but instead the data was stored in the internal memory of the equipment and manually downloaded to a computer at each data collection visit. For the purpose of double checking, meter readings were collected at the electricity meter to be able to compared the accuracy and success of the data collected by the Current Cost smart meters. The internal temperature of every flat was collected by mean of a LogTag temperature data. From comparing the Current Cost smart meter data versus the utility meter readings a huge range of overestimation and underestimation of the actual energy consumption was observed. Regarding the internal temperature monitoring, long periods of lost data was identified. The main factors contributing to these data lost were: Long periods between data collection, wireless signal drop offs, unplugging, tampering and removal of equipment. A normalized energy index, based on utility meter readings, internal temperature and outdoor conditions, was developed to overcome the loss of data and assess the effectiveness of the technology and the behavioral change in the occupants. The normalised energy index provides a methodology to evaluate technology and behavioural changes effect between flats and across seasons

ISEC2005-76077 ANALYSIS OF ELECTRICAL ENERGY SAVINGS FROM DAYLIGHTING THROUGH SKYLIGHTS

ABSTRACT This paper provides a simplified analysis tool to assess the energy saving potential of daylighting for commercial buildings through skylights. Specifically, the impact of daylighting is investigated for various fenestration opening sizes, glazing types, control strategies, and geographic locations. A top floor of a prototypical office building has been considered in the analysis. The results obtained for the office building can be applied to other types of buildings such as retails stores, schools, and warehouses. Based on the simulation analysis results, it was determined that skylight to floor ratio more than 0.3 does not affect significantly the lighting energy savings. An optimum value of skylight to floor area ratio was found to be 0.2 to minimize the annual total building energy use

Evaluation of Ground Source Heat Pump Energy, Demand, and Greenhouse Potential in Colorado Residential Buildings

ABSTRACT This paper summarizes the results of a detailed energy analysis carried out for a typical Colorado residence using three different HVAC systems for 10 distinct locations in Colorado. The HVAC systems considered in the analysis include: 78% efficient furnace with a 13 SEER air conditioner Vertical well ground source heat pump with a heating COP of 3.5 and a cooling EER of 17.1 Slinky ground source heat pump with a heating COP of 3.5 and a cooling EER of 17.

Optimal Control Strategies for Switchable Transparent Insulation Systems Applied to Smart Windows for US Residential Buildings

This paper evaluates the potential energy use and peak demand savings associated with optimal controls of switchable transparent insulation systems (STIS) applied to smart windows for US residential buildings. The optimal controls are developed based on Genetic Algorithm (GA) to identify the automatic settings of the dynamic shades. First, switchable insulation systems and their operation mechanisms are briefly described when combined with smart windows. Then, the GA-based optimization approach is outlined to operate switchable insulation systems applied to windows for a prototypical US residential building. The optimized controls are implemented to reduce heating and cooling energy end-uses for a house located four US locations, during three representative days of swing, summer, and winter seasons. The performance of optimal controller is compared to that obtained using simplified rule-based control sets to operate the dynamic insulation systems. The analysis results indicate that optimized controls of STISs can save up to 81.8% in daily thermal loads compared to the simplified rule-set especially when dwellings are located in hot climates such as that of Phoenix, AZ. Moreover, optimally controlled STISs can reduce electrical peak demand by up to 49.8% compared to the simplified rule-set, indicating significant energy efficiency and demand response potentials of the SIS technology when applied to US residential buildings. &nbsp;</p

Predictive Optimal Control of Active and Passive Building Thermal Storage Inventory

Cooling of commercial buildings contributes significantly to the peak demand placed on an electrical utility grid. Time-of-use electricity rates encourage shifting of electrical loads to off-peak periods at night and weekends. Buildings can respond to these pricing signals by shifting cooling-related thermal loads either by precooling the building's massive structure or the use of active thermal energy storage systems such as ice storage. While these two thermal batteries have been engaged separately in the past, this project investigated the merits of harnessing both storage media concurrently in the context of predictive optimal control. To pursue the analysis, modeling, and simulation research of Phase 1, two separate simulation environments were developed. Based on the new dynamic building simulation program EnergyPlus, a utility rate module, two thermal energy storage models were added. Also, a sequential optimization approach to the cost minimization problem using direct search, gradient-based, and dynamic programming methods was incorporated. The objective function was the total utility bill including the cost of reheat and a time-of-use electricity rate either with or without demand charges. An alternative simulation environment based on TRNSYS and Matlab was developed to allow for comparison and cross-validation with EnergyPlus. The initial evaluation of the theoretical potential of the combined optimal control assumed perfect weather prediction and match between the building model and the actual building counterpart. The analysis showed that the combined utilization leads to cost savings that is significantly greater than either storage but less than the sum of the individual savings. The findings reveal that the cooling-related on-peak electrical demand of commercial buildings can be considerably reduced. A subsequent analysis of the impact of forecasting uncertainty in the required short-term weather forecasts determined that it takes only very simple short-term prediction models to realize almost all of the theoretical potential of this control strategy. Further work evaluated the impact of modeling accuracy on the model-based closed-loop predictive optimal controller to minimize utility cost. The following guidelines have been derived: For an internal heat gain dominated commercial building, reasonable geometry simplifications are acceptable without a loss of cost savings potential. In fact, zoning simplification may improve optimizer performance and save computation time. The mass of the internal structure did not show a strong effect on the optimization. Building construction characteristics were found to impact building passive thermal storage capacity. It is thus advisable to make sure the construction material is well modeled. Zone temperature setpoint profiles and TES performance are strongly affected by mismatches in internal heat gains, especially when they are underestimated. Since they are a key factor in determining the building cooling load, efforts should be made to keep the internal gain mismatch as small as possible. Efficiencies of the building energy systems affect both zone temperature setpoints and active TES operation because of the coupling of the base chiller for building precooling and the icemaking TES chiller. Relative efficiencies of the base and TES chillers will determine the balance of operation of the two chillers. The impact of mismatch in this category may be significant. Next, a parametric analysis was conducted to assess the effects of building mass, utility rate, building location and season, thermal comfort, central plant capacities, and an economizer on the cost saving performance of optimal control for active and passive building thermal storage inventory. The key findings are: (1) Heavy-mass buildings, strong-incentive time-of-use electrical utility rates, and large on-peak cooling loads will likely lead to attractive savings resulting from optimal combined thermal storage control. (2) By using economizer to take advantage of the cool fresh air during the night, the building electrical cost can be reduced by using less mechanical cooling. (3) Larger base chiller and active thermal storage capacities have the potential of shifting more cooling loads to off-peak hours and thus higher savings can be achieved. (4) Optimal combined thermal storage control with a thermal comfort penalty included in the objective function can improve the thermal comfort levels of building occupants when compared to the non-optimized base case. Lab testing conducted in the Larson HVAC Laboratory during Phase 2 showed that the EnergyPlus-based simulation was a surprisingly accurate prediction of the experiment. Therefore, actual savings of building energy costs can be expected by applying optimal controls from simulation results

Evaluation of Ground-Source Variable Refrigerant Flow System for US Office Buildings

This paper evaluates the energy performance of ground-source variable refrigerant flow (VRF) systems to condition office buildings located in various U.S. climates. Specifically, the performance of the ground-source VRF systems was determined and evaluated against that achieved by conventional space heating and cooling systems, including packaged terminal air-conditioners (PTACs), water-source heat pumps (WSHPs), ground-source heat pumps (GSHPs), and water-source VRF systems. A comparative analysis shows that ground-source VRF systems require significantly lower source energy uses than other heating and cooling systems in all U.S. climates, ranging from 21% to 50% for PTACs, from 36% to 52% for WSHPs, from 22% to 49% for GSHPs, and from 4% to 19% for water-source VRFs. These results indicate that ground-source VRFs can be suitable heating and cooling systems for all U.S. climates when designing high-energy-performance commercial buildings

A SIMPLIFIED METHOD TO ESTIMATE COOLING ENERGY SAVINGS FROM NIGHT VENTILATION FOR OFFICE BUILDINGS

ABSTRACT This paper provides a simplified analysis method and to evaluate the potential of night ventilation to save cooling energy for office buildings. Specifically, impacts on cooling energy performance are investigated for various combinations of night ventilation flow rates and duration periods. The analysis results indicate that an increase of ventilation duration period and volume rate leads to greater night ventilation benefits for dwellings located in Denver, CO. However, an increase of the ventilation volume rate above 5 air changes per hour has a little impact on cooling energy savings. When the ventilation period is short (less than 10 hours), and the flow rate is high (more than 3 ACH), the cooling energy savings from night ventilation increase linearly with the ventilation duration period length. A simplified calculation method has been developed based on the results of a series of parametric simulation analyses. Commercial building designers and operators can use the proposed simplified calculation tool to assess the effectiveness of night ventilation in reducing cooling energy use

Analysis Model for Domestic Hot Water Distribution Systems: Preprint

A thermal model was developed to estimate the energy losses from prototypical domestic hot water (DHW) distribution systems for homes. The developed model, using the TRNSYS simulation software, allows researchers and designers to better evaluate the performance of hot water distribution systems in homes. Modeling results were compared with past experimental study results and showed good agreement

Energy productivity analysis framework for buildings : a case study of GCC region

A new analysis framework is developed and applied to assess the benefits of building energy efficiency policies and programs. One of the main advantages of the new energy productivity analysis is that it accounts for both economic and energy performances of energy efficiency actions using only one metric. Specifically, the approach applies the concept of energy productivity to the building sector and accounts for both value added and energy savings of energy efficiency measures. Moreover, the proposed analysis accounts for all quantifiable benefits of energy efficiency programs including economic, environmental, and social. In this paper, the general guidelines for the energy productivity analysis are first described. Then, the analysis is applied to evaluate energy efficiency renewable energy programs for both existing and new buildings in the Gulf Cooperation Council (GCC) countries. The analysis results indicate that retrofitting the existing building stock can provide significant benefits and can improve the energy productivity of the building sector in all GCC countries and free up large energy volumes and investment potentials to the development of other economic sectors. In particular, the analysis indicates that reduction in energy consumption, peak demand, and carbon emissions due to deep retrofit programs for the existing building stock can double the energy productivity of the GCC region

Modeling and Test-and-Rate Methods for Innovative Thermosiphon Solar Water Heaters: Preprint

Conference paper regarding research in modeling and test-and-rate methods for thermosiphon solar domestic water heaters