NiteCool was developed under the Energy Related Environmental Issues in Buildings(EnREI) DOE Programme and is designed especially for the assessment of a range of nightcooling ventilation strategies. The program is based on a single zone ventilation model and isconfigured to analyse a 10m x 6m x3m cell of an office building. It is intended to be used atthe early stages in the design process to help the designer to make informed decisions on theconstruction, opening configuration and operation of the building.
In this paper the energy impact of natural cross ventilation is examined conducting a set of crossventilation experiments in a well insulated apartment of a 5-storey building. The experimental resultscompared with simulation results derived from the combined use of the multizone air flow modelCOMIS and the thermal model Suncode.A 24-hour lasting natural cross ventilation experiment was conducted, to monitor thermal comfortventilation mainly during the day and night time cooling ventilation.
This research is part of project NATVENT (TM), a concerted action of nine institutions ofseven European countries under the Joule-3 program. It aims to open the barriers that blocks theuse of natural ventilation systems in office buildings in cold and moderate climate zones.Natural night-time ventilation cooling is a very effective means to remove the heat,accumulated in the building fabrics during office hours. Moreover, it requires no energy at all.Cooling with natural ventilation has it limits; more than 6 air changes per hour have no morecooling effect.
In France, mechanical cooling is increasingly used in office buildings. This situation isrelated to a demand for a better comfort, the increase of the thermal insulation and internalgains, and the changes in the building design.Nevertheless, in many cases, it is possible to achieve a thermally comfortable environmentby passive means - as thermal inertia, and solar protection of the external envelope - and useof low energy techniques as night or evaporative cooling.
In this paper the potential of night ventilation techniques is investigated. Extended real scalemeasurements have been performed, in three buildings, under free floating and airconditioned operation. Two of the buildings have been studied by using a theoretical modeldeveloped in TRNSYS [1] software. Simulation results have been validated by using themeasured data. Specific studies concerning the indoor air temperature and the cooling load ofthe buildings have been carried out in order to identifj the influence of night ventilationtechniques on the buildings thermal performance.
The planning parameters of a cooling system for ventilation, for example the vaporization andcondensing temperatures, heat capacity flow rates, design temperatures and designtemperature differences have a strong influence on the investment and operating costs.The target of this research is to find economically optimized design parameters byminimizing the present value of investment and the operating costs of the cooling system.
Hokkaido is distinguished from the other island of Japan by having colder winters and cooler summers. The average monthly minimum is about -10 °C and summer daily average maximum around 25°C, so that efficient space heating becomes the dominant aspect But on hot days the temperature may reach 35°C, though for short period of time. There are few houses constructed to prevent overheating ID summer. I have designed and built a house for my family ID Sapporo which has cavity walls of concrete blocks insulated with urethane 100mm thick and deeply recessed, but operable widows.
Thick insulation in buildings offers great potential not only for decreasing cooling load but also for changing its calculation method, and for changing system design, operation or control of the system and the thermal environment of the room. The research results of room air temperature changes in well-insulated buildings, show the effects of the daily swing of outdoor temperature and solar radiation are quite small. A simple calculation method for cooling load based on steady state theories is available for such buildings.
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