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Simulation and Feasibility Study on a ‘Renewable Energy House’ with a Geothermal Heat Pump-Powered Floor Heating System in Cold Climate Regions
Abstract
An actual renewable energy house, equipped with a geothermal heat pump (GHP)-powered floor heating system was investigated and analyzed. Daily annual monitoring between February 2005 ~ February 2006 and real-time continuous system monitoring within selected periods during the winter season between November 2006 ~ January 2007, were carried out in order to establish the actual performance of the system. It emerged that the GHP-powered floor heating system is sufficient for space heating, with the maintenance of near-uniform room temperatures even during the coldest days in a very cold region like Hokkaido, Japan. About 37% average of the floor heat losses are recoverable and more than 50% of the ventilation heat losses are recovered due to various innovative energy-saving techniques built into the system. Annual heat loss from the house estimated by the numerical simulation showed good agreement with the measured annual thermal demand for room heating. The simulation also estimated that annual running costs and Green House Gas (GHG) emissions reductions of 47% and 49% respectively, can be realized with this system compared to an equivalent conventional system. A detailed cost analysis for the GHP-only system revealed that if the cost of fuel oil increases by about 50% from the current value of \80/L, then the payback period for a GHP-powered renewable energy system is about 14 years. This payback period reduces to about 10 years if 30% of the initial cost of the GHP-powered system is externally funded.
... 減， ランニングコストは北海電力の独自のメニューと相まってほぼ半減することなどを実証してきた (Sasaki, et al., 2007)．しかし，GSHP 暖房システムはヨーロッパや北米では 1980 年代以降急速に普及してきた中で，我が国の 普及率は著しく低迷している (Lund, et al., 2004, Yasukawa and Takasugi, 2003, Sanner, et al., 2003 ...
A ground source heat pump (GSHP) heating system is one of the most effective and realistic renewable energy plants which reduce energy consumption and carbon dioxide to be about a half in comparison with an oil heater in cold climate region. In spite of such superior performance, utilization of GSHP has not been extended in Japan, while that has been remarkably increased in Europe and USA. A design tool which is easy to use for builders is required in Japan. Energy balances in an actual renewable energy house, equipped with a GSHP air conditioning system were observed by real-time continuous monitoring systems from 2005 to 2013 and analyzed in Kitami City, Hokkaido, subarctic region, Japan. Real-time continuous monitoring of soil temperature distributions were also carried out from July in 2007. Thermal demand of heating (=heat loss) from house and thermal input caused by residents were well predicted using house configurations and meteorological data (mainly ambient temperature and wind speed). We set the allowable lowest soil temperature at the vicinity of a heat collecting tube 0°C under a common ambient temperature condition in order to maintain healthiness of soil. Seasonal and cumulative changes in soil temperature distributions were successfully analyzed with FEM from the beginning of GSHP operation in 2005 to the end of that in spring, 2014. A prediction method of required lengths of a U-tube to the required heating demands in various domestic cities which have various soil temperatures has been developed. Builders will easily use these simplified methods as a new design tool.
Digital Twins play a vital role in analysing dynamic behaviour and increasing energy efficiency in an interconnected energy system. Energy consumption modelling in buildings is a fundamental part of developing a building energy digital twin, which allows the use of a virtual environment to run ‘what-if’ simulations to explore the impact of design modifications for improving the energy efficiency of buildings. This paper focuses principally on the HVAC demand in a seaport building used as an office space. It explores the flexibility and deployment of heat pumps for emissions reductions and demand response. The office building, located in Middlesbrough, UK was modelled using sensor data on electricity consumption, fuel oil consumption, inside temperature and humidity distribution and the subjective thermal experiences of the building occupants. Modelling errors of less than 6% for the demand for active power and less than 10% for the demand for reactive power were obtained. The models were then deployed for exploration of demand management, demand response and emissions reduction scenarios. The paper reports the potential for 33% cut in CO2 emissions per year by conversion of heating from fuel oil to heat pumps, and a 14% potential reduction in peak electricity load by the deployment of heuristic demand management / demand response controls.
This paper presents the development of modeling, simulation and analysis of a solar pond floor heating system. The developed computer simulation has been used to study the potential of using such a system under climatic conditions in Jordan. It was found that the solar pond heating system could meet most of the winter season in Jordan with Solar fraction in the range 80–100% for at least 2 months of the season. It must be emphasized that the feasibility of such a system is its utilization in district heating and not for individual households due to the limiting economical factors of high capital cost of the solar pond for small domestic applications.
Five different kinds of domestic-size renewable energy system configurations for very cold climate regions were investigated. From detailed numerical modeling and system simulations, it was found that the consumption of fuel oil for the auxiliary boiler in residential-type households can almost be eliminated with a renewable energy system that incorporates photovoltaic panel arrays for electricity generation and two storage tanks: a well-insulated electric water storage tank that services the hot water loads, and a compact boiler/geothermal heat pump tank for room heating during very cold seasons. A reduction of Greenhouse Gas Emissions (GHG) of about 28% was achieved for this system compared to an equivalent conventional system. The near elimination of the use of fuel oil in this system makes it very promising for very cold climate regions in terms of energy savings because the running cost is not so dependent on the unstable nature of global oil prices.
A simplified double grade meteorological data model for the simulation of the annual performance of a domestic-size renewable energy system is proposed. With the model, only two representative days (clearest and cloudiest) during each season of the year are necessary to estimate annual energy balances, carbon emissions and the running costs. The model was chosen in preference to other simplified models based on the error distributions from the results of the continuous simulations in a test period. Detailed numerical simulation studies show that the carbon emissions from the renewable energy system are about 16% of a comparable conventional system. The thermal energy produced by a solar collector during the winter season, however, is insufficient to meet all the loads so that frequent heat pump operations and the auxiliary boiler are necessary in cold climate regions.
Climate data support the “moderate” prediction of climate change (l-1.5°C) rather than the more extreme scenario (4°C or more). The moderate point of view was originally marginalized in the IPCC “consensus” process in both the 1990 First Assessment on Climate Change and in the 1992 Update prepared specifically for the Earth Summit and to provide backing for the Rio Framework Convention on Climate Change.
It is now accepted, based on ground-based data, that the errors in those models are currently between 160% and 360%. If one compares them to the satellite data combined with the land record, the error rises to a maximum of 720%.
In some recognition of this massive error, the 1995 IPCC “consensus” is that warming has been mitigated by sulfate aerosols. However, when that hypothesis is specifically tested, it fails. Further, data required to test the validity of the sulfate enhanced greenhouse models was withheld by the IPCC. despite repeated requests.
This paper presents a two-dimensional simulation model of the heat losses and temperatures in a slab on grade floor with floor heating which is able to dynamically model the floor heating system. The aim of this work is to be able to model, in detail, the influence from the floor construction and foundation on the performance of the floor heating system. The ground-coupled floor heating model is validated against measurements from a single-family house. The simulation model is coupled to a whole-building energy simulation model with inclusion of heat losses and heat supply to the room above the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is important to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further, that the foundation has a large impact on the energy consumption of buildings heated by floor heating. Consequently, this detail should be in focus when designing houses with floor heating.
Dynamic modelling and optimal control of an embedded-piping floor heating system is explored. The physical system consists of a single zone with serpentine tubes embedded in the floor slab. A gas-fired boiler supplies hot water in the tubes. The input energy to the boiler and the mass flow rate of hot water circulating in the tubes is modulated. A numerical solution to the 24-hour optimal control problem, taking into consideration the capacity constraints of the floor heating system, is found. Results show that, by proper choice of objective function, the energy input to the boiler can be minimized while maintaining good zone temperature control. The implementation of the optimal trajectories using PI controllers is also shown.
Efficient radiant heating systems are promising technologies for energy saving in commercial and building sectors together with improving occupant thermal comfort. However, the thermal performance of radiant systems in buildings has not been fully understood and accounted for in currently available building energy simulation software. In this paper, the effects of design parameters on performance of a typical radiant floor heating system have been studied using finite element method. A radiant heating system includes a number of pipes filled with hot water. Therefore, several design parameters such as pipe diameter, type (material), number, thickness and cover of system are affected on the value of transferred heat. In this study, transient conduction, convection and radiation heat transfer mechanisms are considered meanwhile analyzing the typical problem by using a finite element method solver. It is noted that the type and thickness of the floor cover are the most important parameters in the design of radiant heating systems.
Improvement of Thermal Collecting Efficiency of a Photovoltaic/Thermal Hybrid Solar Panel for Cold Climates
- N Endoh
- M Sasaki
- K Doi
N. Endoh, M. Sasaki and K. Doi, Improvement of Thermal Collecting Efficiency of a Photovoltaic/Thermal Hybrid Solar Panel for Cold Climates, Proceedings of the Intern. Conference on Power Engineering-03 (ICOPE-03), 2003