Building Performance Optimization of Net Zero-Energy Buildings - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 266

Design
Variable

Description Options

From 0 to 30 m 2 10 Solar thermal

collector area

31

11 PV collector area From 0 to 70 m 2

71

The aim of Stage -1 is to find representative energy-efficient building
designs, irrespective of the type of heating, cooling, and energy supply
systems. In order to achieve this, the space heating energy demand of the
houseandthepresentworth(PW,definedlater)oftheinfluencingmeasures
(insulationlevel,buildingtightness,windowtype,shadingmethod,andheat
recovery type) are minimized, while a penalty function is applied when the
summer comfort criterion (DH 27 ≥ 150 °Ch) is violated.

According totheFinnish building codeD3, degree-hours (DH 27 )are usedto
measure the summer overheating risk

(5.2)

where T i is the mean air temperature [°C] at the warmest zone and Δ t is a 1
h time period [h].
The minimization work is performed by the two-step optimization approach
(PR_GA) mentioned earlier. The first objective (space heating energy
demand), to be minimized in Stage -1, presents the major energy demand
in the residential building in the cold climate. The second objective (PW)
presentstheinitial andreplacement costs(ICandRC)ofthekeyinfluencing
ESMs (external wall, ceiling, and floor insulation levels, building tightness,
window type, shading method, and heat recovery type). PW is calculated as
follows:

(5.3)