Project drawings

East Façade, Scale 1:100

West Façade, Scale 1:100

North Façade, Multifunctional building, Scale 1:100

South Façade, Private house and Hostel, Scale 1:100

North Façade, Private house, Scale 1:100

North Façade, Hostel, Scale 1:100

Section B-B, Scale 1:100

Section A-A, Scale 1:100

Section C-C, Scale 1:100

house, Scale 1:50

Technical detail, Fixed external shading system - building

Scale 1:20

The aim of this chapter is to explain the passive strategies behind the project choices, before defining the actual energy system, presenting at the same time the software used, DesignBuilder.

To do this, it is necessary to first illustrate the preliminary studies carried out by the NTNU and the SEU and then analyse the building used for the analysis: the private house.

At the same time it is important to describe how the building’s energy model was created using DesignBuilder, defining the parameters and specifications used: the main steps that allowed the creation of a model as consistent as possible with the project are described.

DesignBuilder &

Passive Design

5

Chapter

5.1 Local building energy conditions and analysis

Before proceeding with the definition, first of the passive strategies used in the design and then of the energy system used, it is necessary to clarify in which building context the project is placed and which are the local standards for the existing buildings. To do this, it is appropriate to refer to the analysis carried out, by the NTNU of Trondheim and the SEU of Nanjing on the village historical buildings, to which reference had already been made in section 3.9.

As written, the studies were referred to the old courtyards, which mainly needed interventions for upgrading their energy performance and in some cases of repairing non-structural elements.

The research project that handled the aforementioned analysis, carried on by SEU and NTNU with support from the Norwegian Council of Research (NFR), was realized between years 2013-2016 and was entitled “Energy efficient up-grading of historical villages in Ping Yao area, Shanxi Province, China”.

It was composed by three Work Packages (WP) :

• the first Work Package, WP1, focused on the analysis of the local building traditions, their historical and architectural values together with their technical state.

• the second Work Package (WP2) focused on anthropological studies, necessary to understand how the housing structures ordinarily were used, underlining pros and cons with regard to energy efficiency.

In detail, were analysed daily activities carried out inside and outside the existing dwellings, and how thermal comfort, daylight and ventilation were perceived and influenced activities, feeling of security, belonging and other aspects of residential life.

• the third Work Package (WP3) focused on detailed building physics investigations and energy evaluations and calculation of a building in particular. On the basis of this it was defined a chart of possible interventions that could have been applied to improve the environmental performance of the building, reducing its energy demand.

The analysis in WP3, as said, was carried out on a courtyard house in particular, the Liu Compound, which is also the biggest compound in Hou Ji.

To monitor the house, it has been installed a system denominated HBAS - Historic Building Assessment System – by SEU and NTNU with the support of the Beijing Jiantong Technology. The system aimed at monitoring the winter conditions both of external and internal environment of the house and consisted of one micro-climatic station placed outside the house and four interior thermal environment monitors.

The outside micro-climatic station, placed on the house roof, recorded air temperature values (-30~+70 ± 0.5 °C), relative humidity (0~100 ± 3%), horizontal solar radiation intensity (0.3~3.2 μm with sensitivity 7~14 mV/(kW/

m²) ± 2%), precipitations (≤8 mm/min, φ160 mm ± 4%), wind speed (0~30±1.0 m/s, start at 0.5 m/s) and direction (360° ± 5%,) (Finocchiaro L. et al., 2015).

The four monitoring apparatus located inside the house were placed two in the west room (unheated) and two in the east room (heated). They were able to record data of air and surface radiant temperatures, relative humidity, wet bulb temperature, black bulb temperatures, air flow speed and CO₂ concentration in PPM. They were also able to instantly calculate predicted percentage of dissatisfied (Finocchiaro L. et al., 2015).

As stated in the climate analysis, the HouJi village is located in an area with a climate that is cold-semi arid, according to Koppen-Geiger climate classification. This means that there are large temperature excursion between day and night and that during the year there is a prevalence of cold temperatures, for about six months, fairly short intermediate seasons, and a warm season about three months long with temperatures in some cases very hot; to this are added the strong cold winter winds from Siberia.

Referring to the analysis of WP2 and WP3, to overcome these problems, local homes, both in terms of conformation and construction, are built to protect themselves as much as possible from cold and wind and to disperse as little heat as possible during the cold months.

In fact the local houses use heavy walls in order to store the solar heating during the day while releasing in the night, with the walls that in traditional constructions are made by bricks of burnt loess¹, which guarantees high stability and low thermal conductivity (Finocchiaro L. et al., 2015).

At the same time, buildings are mostly characterized by the presence of an internal courtyard, towards which all the openings face: this was made in order to optimize the access of solar radiation while protecting the house from cold winds. Usually, outside the windows, wooden screens are positioned, equipped with rice paper during the cold season, in order to filter the daylight while regulate ventilation from the courtyards.

To protect the interior from solar radiation, there is a porch along each side of the buildings: this allows to shade the hot summer sun, while allowing low winter sunlight to penetrate inside.

Also from the analysis of WP2 and WP3 the following information concerning the thermal comfort during the year and to the ways for handling discomfort:

• the form and orientation of the buildings, i.e. the narrow yard distributed along the east-west direction, the deep eaves as well as the heavy mass in roof and walls, facilitate thermal comfort.

• the residents have four main measures for improving comfort:

- by shifting between carrying out activities outside and inside

- by using the heated kang and sometimes supplementary extra heating when necessary

- by adapting clothing to shifting temperature

- by using shutters, padded carpets and curtains at doors and windows.

• Local old people usually wear several layers of clothing the whole year

5.1Aeolian sediment formed by the accumulation of windblown lime.

◄ ^{Fig. 5.1}

Section of the building with the location of the three control units.

(Finocchiaro et al., 2015)

◄ ^{Fig. 5.2}

The installed control units.

(Finocchiaro et al., 2015)

▲ ^{Fig. 5.3}

Ground Plan of the Liu Compound with monitored rooms highlighted.

(Finocchiaro et al., 2015)

round, while young people seems to relate to the temperature of the season when it comes to clothing (Finocchiaro L. et al., 2015).

About the daylight handling, simple measurements were made on an overcast day with shifting sky conditions, with a Konica Minolta illuminance meter². The outside illuminance was measured in the middle of the courtyard, which means that there was not full hemisphere of the sky where the measurements were taken. Inside measurements were taken on the kang close to the window, in the middle of the kang and at the edge of the kang.

Therefore the following informations emerged:

• Daylight factor, (100% x indoor illumination/exterior illumination), was calculated to be 3,5 - 4,5% by the window, 1,8 - 3,9% in the middle of the kang, 0,8 - 2,4 by the edge of the kang. In the rear of the room the values were 0,17%

- 0,2%. Although these values were not so accurate, they indicated quite good daylight conditions (Finocchiaro L. et al., 2015).

In the same way the houses of more recent construction, despite having been

5.2 The Konica Minolta illuminance meter is a single element detector that measure photometric bright-ness falling upon a surface, i.e. the amount of light that strikes a surface, in footcandles or in lux.

◄ ^{Fig. 5.4}

Results of three of the coldest days within the monitoring period.

(Finocchiaro L. et al., 2015)

built in the last fifty years, and although using more modern construction standards, seemed to have important deficiencies in terms of comfort regarding the internal air quality, air tightness, as well as isolation.

At the end of the analysis, the following results for winter conditions, were found:

• the measured transmittance values were very high for each building components, both for the wall and floors and for the fixtures, with the exception of the roof.

• temperature fluctuations indoor were reduced from an amplitude of 18 °C to 4 thanks to the effective use of heavy thermal mass

• major challenges in winter were related to air quality and differences among radiant surface temperatures, especially those of windows and floor

• the floor temperature resulted being the most stable one, with values constantly around 3 °C in the unheated room and 12 °C in the heated one

• in the west heated cell, instead, the use of the kang is able to move temperature values within the thermal neutrality range of 14-19 °C

• Significantly high values of carbon dioxide level, up to over 3000 PPM, where 1000 PM is taken as a limit, have been also recorded, during midday in the heated room because of the use of crashed coal and honeycomb briquettes in the Kang.

• there were a high predicted percentage of discomfort in the heated room, always included between 56 and 91% according to the monitoring system

• the mixture of loess and straw used for both bricks and rammed earth over the roof vaults ensured an effective insulation layer. This was confirmed by thermal resistance measures conducted on-site that revealed a low average U-value of 0,65 W/m²K (Finocchiaro L. et al., 2015).

Fig. 5.5 ►

Building’s thermal characteristics obtained from the WP3 analysis.

(Finocchiaro L. et al., 2015)