Movable Insulation Research Articles

Thermal comfort and passive survivability in earthen buildings

Earthen building materials have been regaining popularity due to their environmental, economic, and health advantages. Furthermore, given projected thermal survivability in the face of climate change, passive strategies that minimize use of fossil fuels for operational space conditioning are becoming increasingly necessary. Using the lens of passive survivability, this research investigates the abilities of four earthen wall assemblies (cob, light straw clay, unstabilized rammed earth, insulated unstabilized rammed earth) and three conventional assemblies (concrete masonry unit (CMU), insulated CMU, insulated wood frame) to provide adaptive thermal comfort in six distinct climates, with and without passive heating and cooling systems. Residential dwellings were evaluated through simulation with heat and moisture transport algorithms, showing that passive conditioning is especially beneficial with earth assemblies, bringing 25–70% of uncomfortable annual hours into the adaptive comfort zone, alongside strikingly lower diurnal temperature swings in all examined climates, and in all seasons, than conventional walls. Further investigation into the heat and moisture fluxes reveals that the thermal stability of the earth dwellings is provided in part by moisture sorption and evaporation. Together, for the first time, these results show that the thermal performance of earth assemblies can, with well-designed passive heating and cooling strategies, equal or outperform conventional assemblies in a range of U.S. climates, supporting their expanded inclusion in U.S. building codes. This research provides a novel contribution to the thermal performance optimization of earth construction, critically linking thermal and hygroscopic performance with passive design strategies such as shading, natural ventilation, and movable insulation.

СОВЕРШЕНСТВОВАНИЕ СИСТЕМЫ ТЕПЛОИЗОЛЯЦИИ СТЕН МНОГОКВАРТИРНЫХ ДОМОВ ВТОРИЧНОГО ЖИЛИЩНОГО ФОНДА Г. САРАТОВА

The technical condition of many apartment buildings of the secondary housing stock in Saratov, built from 1977 to 1999, does not meet the current regulatory requirements in the field of creating optimal indoor climate parameters. The system of external thermal insulation of the "wet" type with a rigid fastening of the insulation is very common for the insulation of the external walls of these houses. It has been established that due to the fact that the masonry joints and its irregularities are not filled with mortar, the underestimated thickness of the insulation, a thin layer of the protective layer of plaster, as well as violations of the installation technology of the thermal insulation system, gaps are formed between the insulation plates and the walls, there is an access of cold air to the masonry of the walls, which leads to the appearance of condensate, freezing of walls, an increase in humidity and a decrease in the temperature of the indoor air in apartments. The penetration of cold air through the walls leads to increased heat loss, cooling of the masonry mass and a shift in the "dew point". As a result of the instrumental examination of houses, it is found that the freezing of moistened insulated walls led to an increase in their heat loss by 10-20%. An alternative system of point thermal insulation has been studied, in which the insulation boards are attached to the wall using hinged fasteners, excluding deformation and destruction of the protective plaster layer 10–20 mm thick and the insulation. The optimal thickness of the insulation brand PSB-S 25 for the climatic conditions of the city of Saratov is determined. The technology of mounting a movable thermal insulation system is improved using a deep penetration primer and glue for applying insulation to the plates, which makes it possible to reduce the mass of the structure and reduce the cost of installation work. The effectiveness of the use of a movable thermal insulation system to improve the energy efficiency of multi-apartment buildings of the secondary housing stock in the climatic conditions of Saratov is shown

Heat hazard control in excavation engineering: Numerical simulation of heat transfer characteristics of high temperature tunnel with movable thermal insulation layer

• The use of movable thermal insulation layer (MTIL) in excavating tunnels was proposed. • The thickening of the air layer causes the temperature to rise. • The longer MTIL reduces the thermal insulation capacity. • The moving grid is used to dynamically simulate the MTIL and heading face. The current mine mining has entered the kilometres stage where the high geothermal has become a key factor limiting the tunnel excavation and operation. During the auxiliary ventilation of the mine, the heat exchange between the fresh air and the surrounding rock is serious and cannot meet the cooling demand. Therefore, thermal insulation must be adopted to control the heat transfer. However, the heat exchange between tunnel excavation area and operation area is different, so it is not economical to carry out full tunnel insulation. In order to optimize mine insulation technology and save construction cost, this paper proposes and verifies the feasibility of using movable thermal insulation layer (MTIL) for partial insulation of the excavation tunnel. The dynamic process of tunnel excavation and MTIL following is simulated by using a moving grid method. The results show that MTIL can effectively preserve the air cooling capacity and enhance the ventilation cooling effect. In addition, the thickness of the air layer is proportional to the convective heat flux of the surrounding rock. Whether to install the overall insulation layer and thermal conductivity have little effect on the insulation effect, but the best insulation layer length is 6–8 m. This study provides theoretical and technical support to improve the thermal environment of deep mine excavation work.

Movable window insulation as an instantiation of the adaptive building envelope: An investigation of its cost-effectiveness in the U.S

Improving the performance of building envelope is essential to energy conservation and emission reduction. Adaptive building envelope (ABE) has the potential to effectively reduce building energy consumption at a lower cost. Movable window insulation is an instantiation of the ABE with great application potential in buildings, but it has not been systematically studied. Trying to fill this gap, this paper proposes an automatic control system and a manual control rule for movable window insulation. The energy consumption of double-glazed windows, triple-glazed windows, movable insulation with automatic/manual control, and electrochromic windows is compared in different scenarios using building energy simulation (BES). In some scenarios, the optimal solar heat gain coefficient (SHGC) for windows with movable insulation is higher than that required by the building code. Triple-glazed windows are only effective in reducing the heating energy, while electrochromic windows are only effective in reducing the cooling energy. Infiltration has a great impact on the performance of movable insulation. The net preset value (NPV) analysis shows that movable insulation has a great application potential in Minneapolis, Atlanta, and Phoenix, while triple-glazed windows are only viable in some cases in Minneapolis. Electrochromic windows are not a profitable investment at their current prices.

Effect of movable insulation on performance of the Building integrated Semi-transparent Photovoltaic Thermal (BiSPVT) system for harsh cold climatic conditions: a case study

ABSTRACT Semi-transparent photovoltaic modules are integrated with the building’s rooftop with the provision of movable insulation during off-sunshine hours to reduce the heat losses from room to the ambient. A significant rise in room air temperature of about 6°C at desired hours for cold climatic conditions of Srinagar, India was noted in this study. Also, a metallic drum filled with water has been placed inside the room to reduce the room temperature fluctuations, thus reducing the thermal load leveling. The study is also focused to analyse the simultaneous impact of natural ventilation, direct gain and daylight savings through the south-facing window, thus leading to daylight savings and reducing the dependency on artificial modes of illumination. The effect of water mass and packing factor has also been studied on electrical energy and daylight savings. Analytical expressions for water, metallic drum/tank, room, floor and solar cell temperatures have been derived.

Movable insulation in building integrated semi-transparent photovoltaic thermal (BiSPVT) system

The BiSPVT system involves an integration of semi-transparent photovoltaic (SPV) modules with buildings along with the provision of harvesting thermal energy. The system generates electrical and thermal energy for the building as well as provides day-lighting. However, during summer season the production of thermal energy is higher and thermal demand is lesser as compared to winter season. Also, the higher thermal energy production is unfavourable for the generation of electrical energy by SPV modules. The use of movable insulation (MI) on glazed wall can be one of the method to reduce the thermal energy generation. In this paper, a thermal model has been developed for BiSPVT system and the effect of MI on thermal performance of the system is studied. The energy balance equations are obtained for the inclined SPV modules (top), reinforced cement concrete (RCC) floor (bottom), air of room (SPV modules, floor and four brick/glazed side walls). The room temperature and SPV cell temperature are derived as a function of a) climatic parameters (solar irradiance and ambient temperature), b) design parameters and c) heat transfer coefficients by using the energy balance equations. It is found that by using MI with less or no air cavity thickness, the temperature of room has reduced by 1.93°C. However, the effect of MI on SPV cell temperature is marginal. The proposed model can be utilized to evaluate cell and room temperatures for BiSPVT system installed at different places of the world provided solar irradiance and ambient temperature of that place are known.

Numerical optimization of integrated passive heating and cooling systems yields simple protocols for building energy decarbonization

Passive heating and cooling systems have the potential to reduce space-heating and space-cooling loads in buildings significantly, with minimal embodied energy investment and extremely low operational energy demand. Excellent performance requires movable insulation, operable shading, operable vents, and other adjustable elements, but effective methods for controlling their operation have not yet been established. In particular, the numerical optimization of interdependent passive heating and cooling parameters to maintain thermal comfort has not yet been demonstrated; development of simplified control strategies has not been explored; and resulting load reductions have not been estimated. Here, we investigate these problems in planning for the adaptive reuse of an historic brick office building in the Mediterranean climate of Berkeley, California. Using Hooke-Jeeves and particle-swarm optimizations of passive system parameters in a field-validated EnergyPlus model, constrained to develop monthly schedules responding only to time or temperature, we find that near-optimal configuration and control of passive solar collection eliminate over half of the baseline heating load; likewise, well-controlled shading and natural ventilation eliminate ∼80% of the cooling load. Together, these results reveal the magnitude of the passive space-conditioning resource in this energy-intensive region and demonstrate the power of simple, effective operational strategies to realize substantial energy savings.

Energy and Economic Analysis for Greenhouse Envelope Design

Abstract. The energy consumption of a building is significantly impacted by its envelope design, particularly for greenhouses where coverings typically provide high heat and daylight transmission. Energy and life cycle cost (LCC) analysis were used to identify the most cost-effective cladding design for a greenhouse located in Ottawa, Ontario, Canada (45.4° N) that employs supplemental lighting. The base case envelope design uses single glazing, whereas the two alternative designs consist of replacing the glass with twin-wall polycarbonate and adding foil-faced rigid insulation (permanent or movable) on the interior surface of the glass. All the alternative envelope designs increased electricity consumption for lighting and decreased heating energy use except when permanent or movable insulation was applied to the north wall and in the case of permanent insulation on the north wall plus polycarbonate on the east wall. This demonstrates how the use of reflective opaque insulation on the north wall can be beneficial for redirecting light onto the crops to achieve simultaneous reductions in electricity and heating energy costs. A maximum reduction in LCC of 5.5% (net savings of approximately $130,000) was achieved when permanent insulation was applied to the north and east walls plus polycarbonate on the west wall. This alternative envelope design increased electricity consumption for horticultural lighting by 4.3%, reduced heating energy use by 15.6%, and caused greenhouse gas emissions related to energy consumption to decrease by 14.7%. This analysis demonstrates how energy and economic analysis can be employed to determine the most suitable envelope design based on local climate and economic conditions. Keywords: Artificial lighting, Consistent daily light integral, Energy modeling, Envelope design, Greenhouse, Life cycle cost analysis, Light emitting diode, Local agriculture.

Modeling and experimental validation of heat transfer and energy consumption in an innovative greenhouse structure

The commercial greenhouse is one of the most effective cultivation methods with a yield per cultivated area up to 10 times more than free land cultivation but the use of fossil fuels in this production field is very high. The objectives of this paper are to modeling and experimental evaluation of heat and mass transfer functions in an innovative solar greenhouse with thermal screen. For this propose, a semi-solar greenhouse was designed and constructed at the North-West of Iran in Azerbaijan Province (38°10′N and 46°18′E with elevation of 1364m above the sea level). The inside environment factors include inside air temperature below screen (Ta), inside air temperature above screen (Tas), crop temperature (Tc), inside soil temperature (Ts), cover temperature (Tri) and thermal screen temperature (Tsc) were collected as the experimental data samples. The dynamic heat and mass transfer model used to estimate the temperature in six different points of the semi-solar greenhouse with initial values and consider the crop evapotranspiration. The results showed that dynamic model can predict the inside temperatures in four different points (Ta, Tc, Tri, Ts) with MAPE, RMSE and EF about 5–7%, 1–2°C and 80–91% for greenhouse without thermal screen and about 3–7%, 0.6–1.8°C and 89–96% for six different points of greenhouse with thermal screen (Ta, Tc, Tri, Ts, Tas, Tsc), respectively. The results of using thermal screen at night (12h) in autumn showed that this method can decrease the use of fossil fuels up to 58% and so decrease the final cost and air pollution. This movable insulation caused about 15°C difference between outside and inside air temperature and also made about 6°C difference between Ta and Tas. The experimental results showed that inside thermal screen can decrease the crop temperature fluctuation at night.

The Efficiency of Night Insulation Using Aerogel Filled Polycarbonate Panels During the Heating Season

Heat retention is important in achieving building energy efficiency during the heating season. Minimizing heat loss through a building’s glass envelope during the night is one means of heat retention. Movable insulation is one way to increase the insulation value of the building envelope and reduce heat loss towards the outdoors. This research examines the performance of aerogel filled polycarbonate movable panels in a building located on a Midwestern college campus in the USA. Onsite measurements were taken using air and surface temperature sensors to determine the effectiveness of the system. Computer simulations were run using Therm 7.2 to explore alternative design options. A cost analysis was also performed to evaluate the feasibility of utilizing movable insulation to reduce the heating bills during winter. Results showed that sealed movable insulation reduces heat loss through the glazing by 67.5%. Replacing aerogel with XPS panels reduces this percentage to 64.3%. However, it reduces the cost of the insulation material by 98%.

EVALUATING WINDOW INSULATION FOR COLD CLIMATES

INTRODUCTION In cold climates, a large amount of heat is lost through windows during the winter. For instance, a double-pane window might allow as much as 10 times the amount of heat to leave a house compared to the same area of a typical 2 × 6 wall. It makes sense to upgrade or insulate windows in order to improve the thermal envelope of a home, especially in an area with a long heating season; however, windows are a very expensive component of the building envelope to replace. Replacing a single window can cost several hundred to more than a thousand dollars; therefore, people often resort to cheaper methods to reduce heat loss, such as shutters or curtains. Others may already have high-performance windows, but want to reduce heat loss even further by placing movable insulation over their windows during the cold winter nights. To help guide these decisions, the Cold Climate Housing Research Center (CCHRC) in Fairbanks, Alaska, conducted a study of common window insulation methods and compared them in te...

Survey and evaluation of heating technologies for worldwide agricultural greenhouse applications

This paper reviews and evaluates all the available heating technologies for worldwide agricultural greenhouses and discusses the representative applications of each technology. Available information on the location, ground area, cover materials and performance of the greenhouses coupled with each technology such as water storage (including solar flat plate collectors, ground-source heat pumps and shallow solar ponds), rock bed storage, phase change material storage and earth-to-air heat exchanger system is collected and presented in detail. Using the collected information an attempt has been made to correlate the approximate storage volume or weight of the material required for a given greenhouse area for different storage media under various greenhouse cover materials. These relations can be of great importance to the potential users for the successful development of future applications. Apart from the above-mentioned technologies, a complete review and performance evaluation of other greenhouse heating technologies such as movable insulation, north wall storage, ground air collector and aquifer coupled cavity flow heat exchanger system is also presented. Heating potential (overall performance) of each system under different cover materials along with their advantages, limitations and suitability is also discussed.

06/00201 Cooling performance of roof ponds with gunnybags floating on water surface as compared with movable insulation: Tang, R. and Etzion, Y. Renewable Energy, 2005, 30, (9), 1373–1385

06/00201 Cooling performance of roof ponds with gunnybags floating on water surface as compared with movable insulation: Tang, R. and Etzion, Y. Renewable Energy, 2005, 30, (9), 1373–1385

Modeling of solar passive techniques for roof cooling in arid regions

Thermal models are presented for the typical methods of passive cooling of roof in the arid region of Rajasthan, India. The periodic analysis for hourly variation of roof cooling are presented for bare roof, insulation beneath the roof, evaporative cooling above the roof and roof pond with movable insulation system. Calculations were carried out for a typical summer day of May for Jodhpur (India). The models have been tested with the published experimental data of roof temperature. The predicted values of roof temperature obtained from the proposed models exhibited good agreement with the coefficient of correlation ranging from 0.94 to 0.96 and standard error 1.76 - 2.80 . The 0.05 m of water depth of roof pond with movable insulation is appropriate for better comfort condition in arid region.

Cooling performance of roof ponds with gunny bags floating on water surface as compared with a movable insulation

A roof pond with gunny bags floating on water surface (RPWGB) has been proven to be an efficient evaporative based cooling technique in the previous studies of the authors due to the creation of thermal stratification inside the pond. In this paper, a mathematical model is developed for the investigation of its cooling performance as compared to a roof pond with a movable insulation (RPWMI) under hot dry climatic conditions. This one-dimensional model is based on the new empirical correlations of water evaporation rate from a wetted surface and a free water surface to the ambient air proposed by the authors, and takes into account the response of buildings as a whole to evaporative cooling. Results by simulations indicated that RPWGB performed slightly better than RPWMI, which is widely considered as the most efficient evaporative based roof cooling techniques, except when they are applied to a building with poorly insulated light walls and roof.

Bubble evolution and effects during processing of tungsten : P.Schade. (Osram GmbH, Schwabmüchen, Germany.) Int. J. Refract. Metal/Hard Mater, Vol 20, No 4, 2002, 301–309

The commercial greenhouse is one of the most effective cultivation methods with a yield per cultivated area up to 10 times more than free land cultivation but the use of fossil fuels in this production field is very high. The objectives of this paper are to modeling and experimental evaluation of heat and mass transfer functions in an innovative solar greenhouse with thermal screen. For this propose, a semi-solar greenhouse was designed and constructed at the North-West of Iran in Azerbaijan Province (38°10′N and 46°18′E with elevation of 1364 m above the sea level). The inside environment factors include inside air temperature below screen (Ta), inside air temperature above screen (Tas), crop temperature (Tc), inside soil temperature (Ts), cover temperature (Tri) and thermal screen temperature (Tsc) were collected as the experimental data samples. The dynamic heat and mass transfer model used to estimate the temperature in six different points of the semi-solar greenhouse with initial values and consider the crop evapotranspiration. The results showed that dynamic model can predict the inside temperatures in four different points (Ta, Tc, Tri, Ts) with MAPE, RMSE and EF about 5–7%, 1–2 °C and 80–91% for greenhouse without thermal screen and about 3–7%, 0.6–1.8 °C and 89–96% for six different points of greenhouse with thermal screen (Ta, Tc, Tri, Ts, Tas, Tsc), respectively. The results of using thermal screen at night (12 h) in autumn showed that this method can decrease the use of fossil fuels up to 58% and so decrease the final cost and air pollution. This movable insulation caused about 15 °C difference between outside and inside air temperature and also made about 6 °C difference between Ta and Tas. The experimental results showed that inside thermal screen can decrease the crop temperature fluctuation at night.

Experimental studies on a novel roof pond configuration for the cooling of buildings

A new evaporation based passive cooling technology was tested. The technology is based on the exposure of “floating” wetted cloth to the ambient air. It was compared to various other passive cooling techniques, with very favorable results. Two identical shallow ponds were constructed. One of them was covered with white cotton towels stretched on a densely perforated PVC panel supported by pieces of waterproof polystyrene keeping it just floating on the water surface. Five comparable experiments of different cooling techniques have been carried out. The results indicate that the new cooling technique performed slightly better than the pond with movable insulation, which is widely considered as one of the best roof cooling techniques based on evaporation. It seems that the higher efficiency of the tested technique is due to the thermal stratification created in the water inside the pond, which more effectively resists the transfer of heat gains from the sun and ambient air into the deep water of the pond. In turn, the water temperature near the floor of the pond is lower, thus heat flow from the building to the pond is increased. During the experiment, all the ponds which were compared were ranked according to performance (from best to worse): shaded pond with towels floated on it, pond with towels floated on it and pond with movable insulation, shaded open pond, open pond, covered pond.

A comparison in performance of greenhouses with various shapes: a parametric study

SYNOPSIS This paper presents a comparison in the performance of greenhouses with various shapes for a composite climate (New Delhi). The shapes under study are: even span, uneven span, modified arch, vinery and modified IARI. The performance of the greenhouses has been evaluated with the help of an experimentally validated model. A parametric study has also been presented. The effect of a north wall has been numerically evaluated in an even span, uneven span and modified arch shaped greenhouse. Based on numerical computations, which were carried out for a typical day in summer and one in winter, it could be concluded that: i. greenhouse shape affects the room temperature and thermal load levelling significantly, which is higher in winter as expected; ii. The maximum room temperature (15°C and 20°C) and thermal load levelling (0.10 and 0.12) were increased due to the north wall in winter and summer conditions, respectively; iii. the fluctuations in room temperatures were reduced due to the increase in isothermal mass (water); iv. an increase in the number of air changes along with the use of movable insulation considerably reduced the room temperature in an uneven span greenhouse with a north wall and v. in terms of room temperature and thermal load levelling, the modified arch and vinery shaped greenhouses presented the best performance in summer and winter conditions, respectively.

Off-season cultivation of capsicums in a solar greenhouse

SYNOPSIS The use of solar energy for growing capsicums in pots and in the ground has been studied both under a controlled environment in a solar greenhouse (IIT model) and in an open field during August 2000 to March 2001. Cooling arrangements (natural, forced convection, shading, evaporative cooling) and heating methods (ground air collector, movable insulation during the night) have been employed during the pre-winter and winter periods respectively to maintain the protected environment in the greenhouse. The effects of a north brick wall and the use of movable insulation during the night in the winter months to reduce heat loss from the greenhouse have been incorporated to study the efficacy of the greenhouse. The average height, weight and yield per plant of the greenhouse crop were higher than those of the open field.

Thermal heating of controlled environment greenhouse: a transient analysis

In this paper, an attempt has been made to maintain the plant and room air temperature of a controlled environment greenhouse by using a thermal storage north wall and an integration of a ground air collector. An analytical expression for the plant and room air temperature, based on energy balances for each component, have been derived in terms of climatic as well as design parameters. Numerical computation have been performed for a typical cold day of Delhi, for various temperatures and thermal load levelling. It has been observed that: (i) there is a significant effect of the thermal storage north wall and the ground air collector on the plant and room air temperatures and (ii) thermal load levelling decreases with the increase of the isothermal mass in the case of heating and vice versa for cooling, as per expectations. Experimental validation has also been done for a similar type of greenhouse with movable insulation.