Thermal energy need in Helsinki Metropolitan Area: Difference between revisions

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GWh
GWh
=== Formula ===
=== Formula ===
Q<sub>h</sub> = U * A(T<sub>in</sub>-T<sub>out</sub>) * t
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,
  where Q<sub>h</sub> = Heat flow from building to surroundings,
  U = Buildings overall heat transfer coefficient,
  U = Buildings overall heat transfer coefficient,
  A = Area about which the heat will go trough,
  A = Buildings total surface area (floor, walls and roof),
  T<sub>in</sub> = Indoor temperature,
  T<sub>in</sub> = Indoor temperature,
  T<sub>out</sub> = Outdoor temperature and  
  T<sub>out</sub> = Outdoor temperature and  
  t = Time period of the transfer.
  t = Time period of the transfer.  
Thermal energy what is needed for warm tap water can be calculated as  
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
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,
  where Q<sub>w</sub> = Thermal energy needed for warm tap water,
  p<sub>w</sub> = Water density,
  p<sub>w</sub> = Water density,
  c<sub>p,w</sub> = Specific heat capacity for water,
  c<sub>p,w</sub> = Specific heat capacity for water,
  T<sub>w,warm</sub> = Temperature of warm tap water and  
  T<sub>w,warm</sub> = Temperature of warm tap water and  
  T<sub>w,cold</sub> = Temperature of cold tap water.
  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
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>
Q<sub>total</sub> = Q<sub>w</sub> + Q<sub>h</sub>
where   Q<sub>total</sub> = Year need of thermal energy in city,
  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>h</sub> = Heat flow from building to surroundings and
  Q<sub>w</sub> = Thermal energy needed for warm tap water.
  Q<sub>w</sub> = Thermal energy needed for warm tap water.


== Result ==
== Result ==

Revision as of 08:48, 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; Heating consumption of buildings.

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 = Buildings total surface area (floor, walls and roof),
 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

Total need of thermal energy
. 2007 2013 2020 2025 2030
. [GWh] [GWh] [GWh] [GWh] [GWh]
Helsinki 7475,857243 7535,83639 7605,812062 7655,794684 7705,777307
Vantaa 2129,781022 2216,91573 2318,572889 2391,185146 2463,797402
Espoo 2675,29203 2835,427889 3022,253058 3155,699607 3289,146156
Kauniainen 179,0168745 183,554805 188,8490572 192,6306659 196,4122746
TOTAL 12 459,95 12 771,73 13 135,49 13 362,92 13 655,13

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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