Structural Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 167

Fig. 14 Explanation of time lag and decrement factor on the heat transfer [ 7 ]

It follows that reducing the need for heating/cooling of a residential house can be
done by increasing the thickness of insulation and the use of materials with low
U-value.

5.1.1 Analytical Estimation Based on the Heat Transfer Coef cient

of Building

The thermal performance of a building refers to the process of modeling the energy
transfer between the building and its surroundings. For a conditioned building, it
estimates the heating and cooling load, and hence the sizing and selection of HVAC
equipment can be correctly made. For a non-conditioned building, it calculates
temperature variation inside the building over a speci ed time, and helps one to

estimate the duration of uncomfortable periods. These quanti cations enable one to

determine the effectiveness of the design of a building, and help in evolving
improved designs for realizing energy ef

cient buildings with comfortable indoor

conditions. The lack of proper quanti cation is one of the reasons why the passive

solar architecture is not popular among architects. Occupants would like to know
how much energy might be saved, or the temperature reduced to justify any
additional expense or design change. Architects too need to know the relative
performance of buildings to choose a suitable alternative. Thus, knowledge of the
methods of estimating the performance of buildings is essential to the design of
buildings. EN 15217 provides methods that are required to express the energy
performance of buildings. The certi cate can be based on either the ' measured ' (or

“ operational ” ) or the ' calculated ' (or “ asset ” ) rating.