Sharp JX-9400 Informazioni Techniche Pagina 100

  • Scaricare
  • Aggiungi ai miei manuali
  • Stampa
  • Pagina
    / 211
  • Indice
  • SEGNALIBRI
  • Valutato. / 5. Basato su recensioni clienti
Vedere la pagina 99
indoor air quality at a lower energy cost. Once again, measurements may help in
commissioning and diagnosing failures.
Energy in air handling units
Energy for heating and cooling buildings
Heating and cooling aim to keep a quasi steady and comfort able temperature
indoors, despite variations of the outdoor temperature, and taking into account
the solar radiation heating the building fabric, mainly through windows, and
internal heat gains from occupants and their activities. The amount of energy
needed for this depends on the following parameters:
.
the climate, which is the imposed boundary condition;
.
the opaque parts of the building envelope, the function of which is to protect
the indoor environment against the weather. Reinforced thermal insulation
and good airtightness are essential for this purpose;
.
the transparent parts of this envelope, ensuring daylighting and view, but
also allowing the solar radiation to heat the indoor environment. This passive
solar heating is welcome in the cold season, but induces overheating in the
warm season. Therefore, transparent parts of the envelope should be
equipped with mobile and efficient solar protection to control the passive
solar heating and day lighting;
.
the thermal inertia (thermal mass) of the building fabric, which naturally
stabilizes the indoor temperature;
.
the internal gains resulting from occupants’ activities, which contribute to
heating in the cold season but add to the cooling load in hot season.
It can easily be seen that heating and cooling energy needs depend mainly on
the building design and its location. These energy needs may be satisfied by
different systems, including air conditioning. The systems should be energy
efficient, i.e. satisfy the needs at a minimum energy cost. Among the numerous
heating and cooling systems, we only consider here using air as a medium. It
should be mentioned that, because of its low density, air is a poor heat carrier:
one litre of water carries, in practice, 7–15 times more heat than one cubic metre
of air!
2
Energy for air conditioning
Buildings are primarily ventilated for the purpose of removing the pollutants
generated within them. The air leaving the buildings has the characteristics
(temperature, humidity, chemical composition) of the indoor air. It is replaced
at the same mass airflow rate by air coming from outdoors, which also has its
own charact eristics. Air conditioning is giving or taking heat and water
vapour to or from the outdoor air entering the building to obtain the required
indoor air temperature and humidity. T his needs energy.
Measurements and Measures Related to Energy Efficiency in Ventilation 79
Vedere la pagina 99
1 2 ... 95 96 97 98 99 100 101 102 103 104 105 ... 210 211

Commenti su questo manuale

Nessun commento