The impact of using light-weight external thermal insulation
materials on building surrounding thermal environment in
summer
5 LUO Guozhi, LI Nan, LI Baizhan**
(Faculty of Urban Construction and Environmental Engineering,Chongqing University,
ChongQing 400045)
Brief author introduction:罗国志，（1987-），男，重庆大学在读硕士研究生，主要从事建筑环境与建筑节
能研究。
Correspondance author: 李楠，（1976-），男，博士，副教授，主要从事建筑环境与建筑节能研究. E-mail:
nanlicqu@yahoo.com.cn
Abstract: Introduce a method for calculating surface heat storage coefficient of wall, and make a
calculation on outside surface heat storage coefficient of several common walls with light-weight
10 external thermal insulation materials and the traditional solid clay brick wall. In order to study the
impact of using light-weight external thermal insulation materials on the surface temperature of
external wall, carry out a contrasting experiment between an external insulation room and an
uninsulated room in August, 2010, in Chongqing, China. Calculated result shows that outside surface
heat storage coefficient of the insulated wall is much less than that of the traditional wall, the outside
15 surface heat storage capability of the insulated walls is poor, and the surface temperature has great
fluctuation. Experimental result shows that, during sunny time, surface temperature of external walls of
the insulated room is obviously higher than that of the uninsulated one. In different orientations, due to
different amount of solar radiation and being irradiated in different time, the contrasting temperature
difference (CTD) appears different varied regularity. In a word, using light-weight external thermal
20 insulation materials is bad for building surrounding thermal environment and has a negative impact on
people’s health. Finally, some suggestions on how to eliminate the impact, such as improving the
surface condition of the building envelop, plating vertical greening etc, are put forward.
Keywords: Surface heat storage coefficient; External thermal insulation; Building surrounding thermal
environment
25
0 Introduction
The external wall thermal insulating technology, an effective energy-saving measure, has
been used on a large scale. While meeting the original purpose of reducing building energy
consumption, it shows some other advantages in creating comfortable indoor thermal
30 environment[1][2]. Currently, external wall insulation has 3 forms: external insulation, sandwich
insulation and internal insulation, and the most popular form is the external insulation with
light-weight insulation materials, for the following several reasons: 1. Wide application range; 2.
Almost eliminate the effect of ‘hot bridge’; 3. Protection of the building subject structure; 4.
Convenient for energy efficiency retrofit of existing residential buildings[3].
35 However, the use of light-weight insulation materials has caused a new problem. In summer,
because the light-weight external thermal insulating materials have lower heat storage coefficient,
it makes a noticeable decline in heat storage capability of the outside surface of external wall.
Combined with the good thermal insulation capability of the wall itself, large amount of heat will
accumulate on the outside surface, thus cause the outside surface temperature to rise significantly.
40 For the presence of convective heat transfer effect, the temperature of air near buildings will
increase. The use of light-weight external thermal insulation materials will be likely to deteriorate
the building surrounding thermal environment. However, the problem has not caught people’s
attention. For one aspect, currently, the research of external thermal insulation is mainly focus on
how to reduce energy consumption of buildings, how to improve insulation materials and the
45 effect on indoor thermal environment when using insulation materials[4][5][6]; on the other hand, the
 researches on the building surrounding thermal environment mainly focus on the surface condition
of envelope (absorption rate, reflection rate and rough degree) and vertical greening[7][8]. In the
paper, the problem will be discussed.