Roof Cover Research Articles

SOLAR HEAT COLLECTION CHARACTERISTICS OF A FIBER REINFORCED PLASTIC DRYING HOUSE

This article describes a study of the application of solar energy in a Fiber Reinforced Plastic (FRP) housedesigned for a brown rice drying system. The theoretical heat collection characteristics of an FRP solar drying housewhen empty are presented and compared to experimental results. The purpose of the study was to evaluate: (1) thetemperature variation inside the house; (2) the effect of solar radiation and airflow rate on the temperature differencebetween the air inside and outside the FRP house (temperature rise); and (3) the heat collection efficiency of an FRPhouse when using and not using a solar collector. It was observed both theoretically and experimentally that thetemperature of the air inside the house is higher than that of the outside air, and in the mathematical model, the solarcollector shows a higher temperature than the roof cover. As the airflow rate from the dryer fan inside the houseincreases, temperature rise decreases. For global solar radiation in the range of 100 to 800W/m2, the temperature riseshows an exponential relationship with global solar radiation, and the values of temperature rise are higher when using acollector (5-16C) than when not using one (4-11C). Thus, collector installation inside an FRP solar house has a cleareffect on increasing the air temperature inside the house, which leads to an increase in the heat collection efficiency of thehouse of around 27.23%. In this work, some relationships predicting the optimal house floor size required, the airflowrate per unit mass of product to be dried, and the energy collection are discussed. Then, from the house floor size, airflowrate and collected energy requirements to dry a given amount of product optimally could be calculated.

Demystifying window and door selection for single-family homes in high-wind environments

The failure of the building envelope, including windows, doors and roof coverings, leads to a major portion of the damage of single-family homes wrought by hurricanes. Failure of the building envelope allows wind and water intrusion into the building, and pressurization or depressurization of the interior of a structure may significantly increase differential pressure loads on the structure itself. Damage to windows and doors can result from impact by wind-borne missiles or from the pressure capacity of the unit being exceeded. Commonly available window units may be performance rated (including consideration of air and water intrusion at modest pressures, as well as maximum allowable differential pressure), but there is no readily available means for a house designer, contractor or owner to determine the appropriate rating for a desired window installation (wind-speed claims, while being the simplest to use, are probably the least definable and are the most subject to abuse). Under current design algorithms, the design pressure on windows and doors requires an analysis of each unit based on the dimensions of the unit, the dimensions of the structure, the location of the unit within the structure, and assumptions concerning internal pressurization. This paper reports a design rationale developed under the Blue Sky program for the required pressure capacity of windows that proposes both a window selection tool and a design guide for reducing window pressures (the information is also useful for shutter design and/or selection). The calculated design pressures suggest that most of the windows installed (and being installed) in the 110 mph (fastest mile) zone probably are not rated for the design pressure.

Difficulties with modern pitched roof coverings

Examines modern roof coverings and their associated problems over the past decade. Discusses the designers’ and suppliers’ dependence on and compliance with British Standards. Provides details of the problems and their technical solutions.

Nest-Site Characteristics and Reproductive Success in Magellanic Penguins (Spheniscus magellanicus)

We used cross-sectional, longitudinal, and experimental data to investigate the effects of habitat at the smallest spatial scale-the nest site-on reproductive success of Magellanic Penguins (Spheniscus magellanicus). Over an eight-year period, the amount of nest cover was positively correlated with fledging success. The same pairs tended to be more successful when they had more nest cover, and experimental increases and decreases in cov- er significantly affected survival of nest contents. Other characteristics of nest sites, such as nest type and type of vegetation over the nest, did not affect success. The positive effect of cover resulted mainly from reduced exposure of nest contents to predators during incuba- tion and to high temperatures when chicks were young. Roof cover was positively correlated with fledging success in nests from all areas. Cover on the sides of the nest giving the most protection from the sun was positively correlated with fledging success in warmer sites and with survival of young chicks in all areas. Young chicks at nests with less cover were more likely to move from their nests and to die on hot days. Experimental results indicated that the likelihood of egg detection by predators decreased with increasing nest cover. Height of nest entrance was a significant predictor of egg loss, suggesting that accessibility of nest contents to predators was an important component of predation risk. Thermal properties of nests and risk of predation were related; predation of nest contents was more likely when adults were absent, and during hot weather adults were more often absent from nests with little cover. Although the effect of cover on success was small relative to the large yearly variation in success due to food conditions, cover is likely to influence lifetime reproductive success substantially. Large and long-term data sets and experimental approaches may be necessary to identify subtle but biologically important factors among long-lived organisms that inhabit variable environments. Received 18 November 1996, accepted 29 May 1997.

Performance of modern products for underlay in residential buildings

The performance of some modern products intended for underlayment in steep roofs was studied. Properties considered were durability against thermal degradation and against water. Also the effect of combinations of water, heat and cold were studied as well as natural ageing. The effect of water flowing over installed products was also studied. The studied products were foils or sheets, most of them containing polymers. The products were found to function properly when installed. Some of them declined in strength with ageing. Products with cellulose fibres started to curve and bend by water load. Some plastic foils could be permanently deformed when mechanically loaded. Some of the foil products also had problems with water-pool formation at the eaves, when prone to flowing water at low slopes. These processes do not necessarily result in leakages but may be harmful to the function of the roof cover. It seems important to install the outer covering quite soon after mounting the underlay, as the underlay products studied have limited durability against natural ageing or water. When properly used they seem to have a good and economic performance.

劣化した屋根用塗装鋼板の表面性状と滑雪性に関する研究

Careful consideration was given to the change in the snow-sliding performance of coated steel sheets roofs due to deterioration in snowfall area. Samples of the steel sheets that had deteriorated were collected from those actually used as roof coverings in Sapporo City.As a result of these experiments, the dynamic friction resistance of those sheets which have been used for five years or more is on the upward trend. And no marked change can be found until fifteen years. After that, as irregularities on the outer surface increase, the above resestance has become much more larger.

The surveying of stone slate roofs in the Yorkshire Dales

Deals with the surveying of stone slate roofs within the Yorkshire Dales National Park. Initially examines the history of stone slating in the area and then identifies problems today due to lack of new materials and loss of craft techniques. Gives practical advice on the surveying of the roof coverings and preliminary guidance on preparation and equipment. This is then followed by a standard format approach to the survey dealing with the coverings, ridge, verge and other details, followed by the internal inspection and condition of the slates, battens and fixings. Discusses costings and concludes that a standard format is the most suitable and that the building professional should be aware of regional variations when working with the material. Detailed surveys of the roof will allow repairs and replacement to be specified confidently.

Mechanics of triangle zones and passive-roof duplexes: implications of finite-element models

Finite-element models of passive-roof duplexes simulate the evolution and distribution of fault slip and deformation as functions of boundary conditions, friction on the roof fault, cover strength and amount of overburden. A foreland buttress is essential for backthrust displacement in the models. This foreland buttress is analogous to a pin line between the cover and footwall forelandward of the triangle zone in a balanced cross section, and could be caused by a stratigraphic pinchout of the upper detachment or a strong cover in the foreland. With boundary conditions that prevent the cover from slipping toward the hinterland relative to the wedge, incipient forethrust and backthrust ramps (zones of high equivalent plastic strain) cut through the cover. In the models, there is more backthrust displacement with a lower friction coefficient on the upper detachment and with a stronger cover. Because of pressure dependence, both fault strength and material strength increase with increasing overburden. Therefore, the effect of overburden on backthrust displacement is determined by the nature of the pressure dependencies for fault friction and material strength. In models with multiple imbricate faults, the distribution of equivalent plastic strain adjacent to each fault is similar to that in single-fault models, with differences resulting from bending strains in the wedge and cover. The strain distribution in the cover of the models is similar to that above natural passive-roof duplexes, characterized by layer-parallel shortening above the tip of each horse in the duplex.

Non‐destructive evaluation of heat‐welded seams of roof coverings

L'homographie des cordons de soudure par fusion sur produits en bitume elastomere peut etre etudiee par la methode de l'echo d'impulsion ulttrasonore. Un echo de resonance marque en provenance de la zone de soudure est indicateur de l'absence d'homogeneite du cordon. Le defaut peut alors etre calibre en differents types de structure, determines grâce aux differentes configurations d'echo. Des etudes complementaires sont necessaires pour optimiser les donnees obtenues.

Joint strength of single-ply roof coverings adhered to sheet metal

Heat-welded joints between organic roof-covering materials and sheet metal were studied for three different products of single-ply roof covering. Joints were formed at different temperatures of roof covering and sheet metal. It was found that fairly strong seams could be formed when the welding temperature was high enough, although overheating was detrimental. Roof covering and sheet metal should both be heated.

Regarding surface properties and snow-sliding performance of deteriorated steel sheet for roofing

Careful consideration was given to the change in the snow-sliding performance of coated steel sheets roofs due to deterioration in snowfall area. Samples of the steel sheets that had deteriorated were collected from those actually used as roof coverings in Sapporo City.As a result of these experiments, the dynamic friction resistance of those sheets which have been used for five years or more is on the upward trend. And no marked change can be found until fifteen years. After that, as irregularities on the outer surface increase, the above resestance has become much more larger.

Single-ply roof coverings on flat roofs

Single-ply roof coverings on flat roofs

Dynamic mechanical properties of single-ply roof coverings for low-slope roofs and the influence of water

The results of five different commercial single-ply roof-covering products for low-slope roofs, i.e. atactic polypropylene (APP)-modified bitumen, styrene-butadiene-styrene copolymer (SBS)-modified bitumen, ethylene-copolymerized bitumen (ECB), plasticized PVC and ethylene-propylene-diene-methylene (EPDM)-rubber, studied by dynamic mechanical thermal analysis are summarized in this paper. Two samples of each product were tested, one which had only been conditioned at 20 °C, 50% relative humidity, and another which had been immersed in distilled water at 50 °C for 4000 h. The difference in the dynamic properties at the glass transition region of the two samples is discussed. The influence of water immersion on material properties such as T g and T onset was observed for the products of APP-modified bitumen, SBS-modified bitumen and plasticized PVC. The changes in these material properties may have significance for the durability of the products. Dynamic mechanical thermal analysis can be a useful tool for characterizing products used for single-ply roof coverings of low-slope roofs. It may be useful in understanding how different types of products behave in application with different types of dynamic stresses.

Solar thermal analysis of honeycomb roof cover system for energy conservation in an air-conditioned building

Periodic analysis of solar heat transfer processes in a system comprising an air-filled honeycomb placed on the concrete roof top of an air-conditioned building was carried out to investigate solar thermal gain and assess the effectiveness of system components. An explicit expression for the heat flux entering the indoor space is derived. Results of calculations corresponding to a typical winter day at Boulder, USA, (40°N) show that the solar gain (heat flux) of the system increases with the depth of honeycomb and a panel of depth 10–15 cm seems optimum for such an application.

Effects of Diencephalic Roof Covering on the Locomotor Activity Rhythm in the Newt

Effects of Diencephalic Roof Covering on the Locomotor Activity Rhythm in the Newt

Wind loading and fatigue behaviour of fixings and bondings of roof coverings

The windaction on typical roofing systems for flat roofed buildings, i.e. loose laid, mechanically fixed roofing membranes and cold bonding of roofing membranes, is described. The fatigue behaviour of such roofing systems is given. Loading cycles for proof testing of those roofing systems and results of proof testing and forensic testing are presented.

Honeycomb roof cover system for passive solar space heating

This paper presents an analysis of the passive space heating characteristics of an air-filled honeycomb placed on the concrete roof-top of a building. In particular, the solar transmittance and heat losses through the honeycomb cover system have been investigated to estimate the solar collection efficiency and heat retention duration of the system. Numerical calculations are carried out for a typical winter day in New Delhi (28°N). and a relatively colder day in Boulder (40°N). It is found that the honeycomb cover system considerably increases the heat collection efficiency of the roof. It also reduces the nocturnal heat losses to enable longer heat retention. The system is more effective in colder climates.

Evaluation of aging characteristics of bituminous roof coverings by thermo-mechanical analysis (TMA)

Four bituminous roof coverings have been subjected to various aging procedures including heat, UV irradiation and temperature/rain cycling. A specially modified TMA technique has been used for evaluation, depending on measurements of softening temperature. A comparison with mechanical test data has also been made. Some conclusions have been drawn with respect to influence of heat and UV radiation on the rate of degradation.

How do Foams Perform under Fire Conditions?

The fire performance of foams does not, as often stated, solely depend on the chemical and physical properties of the type of material used. On the contrary, it is determined by many other factors including its form, any interactions with other materials used and the design of the finished product. In order to obtain a realistic assessment of their fire hazard, it is of prime importance to test the fire performance of finished foam systems under normal operating conditions. Thus, several examples of large-scale fire tests for different foams as parts of roof coverings, external walls and as packaging materials are given. The results show that systems containing these foams do not present an unacceptable fire hazard.

Wind Loading on a Pyramidal Roof Structure

This paper deals with the investigation of wind loading on the pyramidal roof structure of the Church of St Michael in Newton, Wirral, Cheshire, England, by wind tunnel tests on a 1/48 scale model. The roof of the model was flat in the peripheral region of the building while in the inner region there was a grouping of four pyramidal roofs. Wind tunnel experiments were carried out; wind pressure distribution and contours of wind pressure on all surfaces of the pyramid roofs were determined for four principal wind directions. The average suctions on the roof were evaluated. The highest point suction encountered was — 4q whilst the maximum average suction on the roof was —0·86q. The results obtained from wind tunnel tests were used for the design of pyramidal roof structures and roof coverings for which localised high suctions were very significant.