Passive Heating Concepts Research Articles

Energy efficiency and supplement interior comfort with passive solar heating in Saharan climate

ABSTRACTThe huge energy amount demanded for heating, during cold seasons is among the most complicated and cost energy supply problems in our life. Since free solar gains are spreading evenly on a part of the ground surface, the contribution of this passive heating concept has been assessed, through the current work. One must determine its impact on both the variation in energy efficiency and the main comfort parameters. The heat produced by the sun’s rays constitutes a promising option source of heating supply. In this view, a recent approach has been implemented in the way to create an energetic label by providing parameters, occupancy scenarios, lifestyle and all required data. Based on the assessed climate data, recorded on Saharan area, it has been averred that the passive solar heating represents only about 8.06% from the total energy supply, provided by the used thermally insulated building. The results show that the total needed energy consumption is about 441.27 kWh/m2/year ‘type F: building with high energy demand’. According to the energy labelling of buildings and regarding some considerable measures, the mentioned current structure type will be involved with the buildings that have an energy label of type D.

Energy conservation in honey storage building using Trombe wall

This paper investigates energy conservation, mitigation of CO 2 emissions and economics of retrofitting for a honey storage building with Trombe wall for winter heating application. The passive heating potential of Trombe wall for a honey storage building was estimated using TRNSYS building simulation software. This honey storage building is located at Gwalior (latitude: 26°14′N) in India. During winter months, the room air temperature of building falls below the required temperature range of 18–27 °C which is suitable for honey storage. So, the room air temperature range is maintained in the building using a 2.3 kW capacity electrical oil filled radiator (or room air heater) which accounts for the major energy consumption of the building on an annual basis. On account of which there are significant CO 2 emissions into the atmosphere from the honey storage building. Hence, this case study was conducted to recommend the passive heating concept to the stakeholders of the building so as to conserve the energy requirement for room air heating. The investigation showed that the room air temperature can be easily maintained in the range suitable for honey storage using a vented Trombe wall. The experimental work was carried out for the existing building on a typical clear day of harsh winter month of January to validate the results of TRNSYS model of the present building. The statistical error analysis showed a good agreement between model and experimental results. This investigation concludes that there is potential of energy conservation up to 3312 kWh/year and associated reduction in CO 2 emissions (∼33 tonne/year) using a Trombe wall. Also, the retrofitting of building is economically viable as the simple payback period is only about 7 months.

Application of U and g values for sizing passive heating concepts

The concept of solar gain factor and the overall heat loss coefficient, obtained for solar passive heating concepts, has been extended to size these as building elements for different climatic conditions. As an example, India's four climatic zones where winter heating is required have been selected and the required area of passive heating concepts calculated by a steady-state analysis applied to a single zone building. The size of various concepts expressed as percentages of the south wall area are independent of the building size as confirmed for the case of army shelters in cold and sunny conditions of Laddakh in northern India. For a building with capacity effects in walls and roof, the dynamic simulation confirms the values of room temperature at a comfortable level assumed to be 18.3°C in the steady-state analysis.

Solar heat gain factors and heat loss coefficients for passive heating concepts

The concept of solar heat gain factor has been introduced for calculating the net energy gain of passive heating elements and other components of a building as a result of incident solar radiation. For passive heating concepts (namely, the direct gain, mass wall, water wall, Trombe wall, and solarium), exact analytical expressions have been obtained for the solar heat gain factors and the corresponding overall heat loss coefficients. These will allow a building designer to calculate immediately the overall heat gain/loss in a building. Numerical calculations have been done for typical values of solar radiation and ambient temperature of typical climatic conditions in India. The method has been compared with the other methods reported in the literature so far. A good comparison is found between the earlier methods and the method of using solar gain factors and the corresponding heat transfer values.

A simple procedure for selection and sizing of indirect passive solar heating systems

Equivalent sol-air temperatures have been defined for four indirect gain passive solar heating concepts, namely, mass wall, water wall, Trombe wall and solarium. Steady state thermal efficiencies have also been defined as a measure of the ability of each system to deliver heat into the living space. Design curves have been developed which relate the average instantaneous solar radiation incident on the passive element to thermal efficiency for different values of ambient temperature. These curves are useful in selection of an appropriate passive heating concept for a particular location. It is inferred that a solarium is most effective at very low levels of incident radiation and low ambient temperature. Water walls and Trombe walls are most efficient at higher levels of incident radiation. A simple procedure has been developed for a first approximation of sizing the selected system using these design curves and a minimum of meteorological information, namely, monthly average of daily global solar radiation, monthly average maximum and minimum ambient temperatures.

Evaluation of complex heat transfer coefficients for passive heating concepts

Passive heating concepts namely Trombe wall, Water wall and Trans wall have been analysed to obtain overall heat transfer coefficients for average values and for time-dependent variations. The numerical values have been obtained and tabulated for various wall thicknesses.

Analysis of the direct gain concept for non-conditioned buildings

Based on periodic solutions of the dimensionless heat conduction equations, an analytical model is developed to study the direct gain passive heating concept for non-conditioned buildings. The effect of multireflections inside the building has also been taken into account. Numerical calculations are also carried out for a mild winter climate (New Delhi, India) and a harsh winter climate (Boulder, Colo.,U.S.A.). The results indicate that, for a mild winter climate, a floor area equal to that of the glazed area is able to provide comfortable conditions, while for a harsh winter climate, the floor area/glazed area ratio may be 1 2 or 3 4 , and auxiliary energy also has to be used.

A passive-heated building for a cool, humid climate in India

This paper describes the design and thermal performance of a passive-heated building for the cool, humid climatic conditions of Srinagar, India. The annual climatic variations of Srinagar are from a cold and very humid winter to a temperate, humid late summer. Thus, the major trend is creating comfort conditions by appropriate heating. The design discussed here therefore uses passive heating concepts. Special care is taken to prevent wasteful heat losses during the winter and unwanted heat gains in the summer. In order to ascertain the performance of the design, a thermal analysis has been carried out. The performance was found to be satisfactory.

Periodic analysis of a transwall: A passive heating concept

A periodic analysis of the novel ‘transwall’ for passive heating is described and the thermal flux entering an air-conditioned space through the ‘transwall’ is evaluated. Numerical calculations have been performed corresponding to the meteorological data of the 11th of January at Boulder, Colorado, USA, i.e. for a harsh North American winter's day.

Periodic analysis of Roof Radiation Trap System: A passive heating concept

The thermal flux coming into an air-conditioned space through a ‘Roof Radiation Trap System’ has been evaluated. Numerical calculations have been performed corresponding to the meteorological data on 11 January at Boulder, Colorado (USA), a harsh North American winter day. Subsequent parametric studies using the simulation indicated that the critical parameters were the width of the air gap and that of the concrete roof through which the thermal flux passes into the room.

Analysis of passive heating concepts

Based on Fourier series solution of the heat conduction equation, a mathematical model has been developed to analyse the thermal performance of some typical passive heating concepts, namely the Trombe wall, Water wall and Solarium in two cases, (i) when the glazing is left uncovered thoughout and (ii) when the glazing is covered with an insulation during off sunshine hours. The model yields analytical expressions for the time dependent heat flux entering into the living space, which is assumed to be at a constant temperature corresponding to an air conditioned room. Numerical calculations corresponding to the meteorological data of a typical cold winter day in North America (Boulder, 13 January) show that from the point of view of thermal load levelling and average heat flux into the room, the solarium is best when the south glazing is not covered with a night insulation. In the case when night insulation is used a water wall is, however, found to be the best; a 0.10 m wide water wall followed by a 0.22 m thick concrete wall gives almost a constant heat flux into the living space.