Difference between revisions of "Thermal energy need in Helsinki Metropolitan Area"

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=== Data ===
 
=== Data ===
 +
Consumption of district heating in Helsinki metropolitan area in year 2007 <ref> Adato Energia Oy. 2008. District heating in Finland. Kaukolämpötilasto 2007 </ref>.
 +
 +
Building stock of Helsinki metropolitan area <ref> Statistics of Finland. 2008. Building stock 2000 & 2007 </ref>.
 +
 +
Helsinki Metropolitan area Council's (YTV) report of floor area and population changes in Helsinki metropolitan area to 2025 <ref> Helsinki metropolitan area Council. 2003. PKS tulevaisuudenkuva 2025 (in Finnish) </ref>
 +
 +
Global warming and changes in outdoor temperature.
 +
 +
  
 
=== Causality ===
 
=== Causality ===
  
 
=== Unit ===
 
=== Unit ===
−
 
+
GWh
 
=== Formula ===
 
=== Formula ===
 +
Q<sub>h</sub> = U * A(T<sub>in</sub>-T<sub>out</sub>) * t
 +
where   Q<sub>h</sub> = Heat flow from building to surroundings,
 +
  U = Buildings overall heat transfer coefficient,
 +
  A = Area about which the heat will go trough,
 +
  T<sub>in</sub> = Indoor temperature,
 +
  T<sub>out</sub> = Outdoor temperature and
 +
  t = Time period of the transfer.
 +
Thermal energy what is needed for warm tap water can be calculated as
 +
Q<sub>w</sub> = c<sub>p,w</sub> * p<sub>w</sub> * q<sub>m,w</sub> * (T<sub>w,warm</sub> - T<sub>w,cold</sub>) * t
 +
where   Q<sub>w</sub> = Thermal energy needed for warm tap water,
 +
  p<sub>w</sub> = Water density,
 +
  c<sub>p,w</sub> = Specific heat capacity for water,
 +
  T<sub>w,warm</sub> = Temperature of warm tap water and
 +
  T<sub>w,cold</sub> = Temperature of cold tap water.
 +
Other thermal energy leaks are estimated to be negligible. A city’s need of thermal energy in a year can be then estimated to be sum of single buildings need of thermal energy. Thus a city’s total need of thermal energy can be calculated as
 +
Q<sub>total</sub> = Q<sub>w</sub> + Q<sub>h</sub>
 +
where   Q<sub>total</sub> = Year need of thermal energy in city,
 +
  Q<sub>h</sub> = Heat flow from building to surroundings and
 +
  Q<sub>w</sub> = Thermal energy needed for warm tap water.
  
 
== Result ==
 
== Result ==

Revision as of 07:16, 20 April 2009



Scope

Defines how thermal energy need will change in the future in Helsinki metropolitan area. Calculations are done by day degree method which is explained here .

Definition

Data

Consumption of district heating in Helsinki metropolitan area in year 2007 [1].

Building stock of Helsinki metropolitan area [2].

Helsinki Metropolitan area Council's (YTV) report of floor area and population changes in Helsinki metropolitan area to 2025 [3]

Global warming and changes in outdoor temperature.


Causality

Unit

GWh

Formula

Qh = U * A(Tin-Tout) * t where Qh = Heat flow from building to surroundings, U = Buildings overall heat transfer coefficient, A = Area about which the heat will go trough, Tin = Indoor temperature, Tout = Outdoor temperature and t = Time period of the transfer. Thermal energy what is needed for warm tap water can be calculated as Qw = cp,w * pw * qm,w * (Tw,warm - Tw,cold) * t where Qw = Thermal energy needed for warm tap water, pw = Water density, cp,w = Specific heat capacity for water, Tw,warm = Temperature of warm tap water and Tw,cold = Temperature of cold tap water. Other thermal energy leaks are estimated to be negligible. A city’s need of thermal energy in a year can be then estimated to be sum of single buildings need of thermal energy. Thus a city’s total need of thermal energy can be calculated as Qtotal = Qw + Qh where Qtotal = Year need of thermal energy in city, Qh = Heat flow from building to surroundings and Qw = Thermal energy needed for warm tap water.

Result

See also

References

  1. ↑ Adato Energia Oy. 2008. District heating in Finland. Kaukolämpötilasto 2007
  2. ↑ Statistics of Finland. 2008. Building stock 2000 & 2007
  3. ↑ Helsinki metropolitan area Council. 2003. PKS tulevaisuudenkuva 2025 (in Finnish)
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