| 1. |
- Gustafsson, Stig-Inge, et al.
(författare)
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Insulation and Bivalent Heating System Optimization : Residential Housing Retrofits and Time-Of-Use Tariffs for Electricity
- 1989
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 34:4, s. 303-315
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Tidskriftsartikel (refereegranskat)abstract
- Time-of-use tariffs, which reflect the cost of producing one extra unit of electricity, will be more common in the future. In Sweden the electricity unit price will be high during the winter and cheaper during the summer. A bivalent heating system, where an oil-fired boiler takes care of the peak load, when the electricity price is high, and a heat pump the base load, may decrease the cost of space heating substantially. However, insulation retrofits are also likely to reduce the peak space-heating load in a building. This paper shows how a bivalent heating system can be optimized while also considering the insulation measures. The optimization is elaborated by the use of a mixed integer programming model and the result is compared with a derivative optimization method used in the OPERA (optimal energy retrofit advisory) model. Both models use the life-cycle cost (LCC) as a ranking criterion, i.e. when the lowest LCC for the building is achieved, no better retrofit combination exists for the remaining life of the building.
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| 2. |
- Gustafsson, Stig-Inge, et al.
(författare)
-
Life-Cycle Cost Minimization Considering Retrofits in Multi-Family Residences
- 1989
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 14:1, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- When a building is to be renovated it is important to implement the optimal retrofit combination. If this strategy is neglected it might not be profitable to change the building in order to improve it as an energy system. This paper deals with energy retrofits and how the strategy can be optimized considering one specific building. The best solution is found when the life-cycle cost for the building is minimal, and building envelope, ventilation and heating system retrofits are combined. In order to solve the problem, a mathematical model, OPtimal Energy Retrofit Advisory (OPERA), has been developed. Energy balance calculations are used in which the free energy from solar radiation and from appliances is taken into proper account. The interaction between different retrofits is emphasized. Provided that the optimal solution is implemented, the retrofits in the combination will have a minor interaction which, for most cases, could be neglected. This will also imply that the order of implementation is of no, or minor, importance. A case study for a real building sited in Malmö, Sweden, and a sensitivity analysis for some critical input parameters are discussed.
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| 3. |
- Gustafsson, Stig-Inge, et al.
(författare)
-
Optimization of Bivalent Heating Systems Considering Time-Of-Use Tariffs for Electricity
- 1989
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Ingår i: Heat Recovery Systems and CHP. - : Elsevier BV. - 0890-4332. ; 9:2, s. 127-131
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Tidskriftsartikel (refereegranskat)abstract
- The cost for producing energy differs a lot due to the load coupled to the distribution grid. In Sweden the load has its maximum during the winter because of the climate. The cost for producing one extra unit of energy is then about 0.50 SEK kWh−1 (1 US$ = 6 SEK), while during summer the cost can be ten times lower. In order to encourage the consumers to save energy during the winter when the cost is high, it may be important to introduce a time-of-use tariff, which reflects the cost for producing the energy. Such a rate is present in Malmö, Sweden. when retrofitting buildings it is of course important to consider the applicable rate for energy, in order to decide the optimal retrofit strategy. In the time-of-use rate the peak load is expensive and a heating system that will use less of the peak energy becomes very desirable. A bivalent heating system, where the base load is provided by a heat pump and an oil boiler takes care of the building peak load can sometimes be found to be the best solution. In this paper two different methods are used for the optimization of such a bivalent heating system. One method uses derivative considerations, the OPERA model, while the other uses linear programming.
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| 4. |
- Gustafsson, Stig-Inge, et al.
(författare)
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Why is Life-Cycle Costing Important when Retrofitting Buildings
- 1988
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 12:2, s. 233-242
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Tidskriftsartikel (refereegranskat)abstract
- Using life-cycle costing (LCC) gives us a means to find the best retrofit strategy for an apartment block. This method also shows us how important it is to consider the whole existing building as an energy system. If the best heating system is put into the house almost every shield retrofit is unprofitable. Having heating systems, with high variable costs combined with exhaust ventilation air pumps, sometimes makes it unprofitable to caulk the windows and doors. This article also shows the importance of using the accurate prices for the energy. Short-range marginal costs (SMRC) gives different retrofit strategies than normal tariffs used today. This also means that the retrofits do not correspond to the optimal use of the total national energy system and already scarce resources are used unnecessarily.
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| 5. |
- Gustafsson, Stig-Inge, et al.
(författare)
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Differential Rates for District Heating and the Influence on the Optimal Retrofit Strategy for Multi-Family Buildings
- 1987
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; 7:4, s. 337-341
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Tidskriftsartikel (refereegranskat)abstract
- When renovating existing multi-family buildings it is very important to implement the best retrofit strategy possible in order to minimize the remaining life-cycle cost for the building. If the building is heated with district heating this strategy of course changes due to the energy rate used by the utility. It is also very important for the utility that the consumer is encouraged to save energy when there is a need for it, i.e. during peak load conditions. Our paper shows that an accurate cost differential rate provides all these facilities.
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