Technical Solution ▎70,000 m² Ultralow Energy Consumption Residential Project in Shishou, Hubei

The book "Ultralow Energy Consumption Building Industry Practice," planned and compiled by the Green Building Study Group, has been published by Sichuan Science and Technology Press. The "Project" section includes 11 ultralow energy consumption building projects, introducing their planning and design, energy-saving strategies, technical solutions, operation and maintenance management, and energy consumption data. The project introduced in this article is: Litian Lakeside Ultralow Energy Consumption Residential Project in Shishou City , authored by Chen Jie of Litian Commercial Operation Management Co., Ltd. and Litian Waterproof Technology Co., Ltd.

 

Abstract

The project is a green and low-carbon energy-saving building designed and constructed in accordance with the Hubei Provincial "Energy-Saving Design Standard for Passive Ultralow Energy Consumption Residential Buildings," the Ministry of Housing and Urban-Rural Development's "Technical Guidelines for Passive Ultralow Energy Consumption Green (Residential) Buildings" (Trial), the Beijing Kangju Center certification standard, and green building evaluation standards. It mainly showcases the cutting-edge concepts, high-tech R&D, and application of passive house ultralow energy consumption buildings.

 

Keywords
 

Ultralow energy consumption; Passive house; Residential building; Five major systems; Precise calculation; Independent research and development

 

 

Project Overview

 

The "Litian Lakeside" demonstration project of passive ultralow energy consumption residential buildings in Hubei Province is located south of Bijia Mountain and west of Chenjia Lake West Road in Shishou City, Hubei Province. The planned land area is 27,825.17 m², the building area is 6,275.97 m², there are a total of 8 residential buildings, and the total construction area is 71,094.38 m².

 

Panoramic bird's-eye view of the "Litian Lakeside" project

Technical Solution

 

Specific technical solutions include a high-performance exterior wall insulation system, high-performance aluminum-plastic co-extrusion doors and windows, steel composite entrance doors, thermal bridge-free design, high airtightness of the entire building, a high-efficiency full cold and heat exchange ventilation system, and an intelligent control and monitoring management system for equipment.

 

1 Building Design Scheme

 

Shape Factor

The shape factor of this project meets the "Hubei Provincial Energy-Saving Design Standard for Low-Energy Consumption Residential Buildings," with a shape factor of 0.4.

 

Window-Wall Ratio

The actual window-wall ratio of each facade of this project is: 0.19 for the east, 0.35 for the south, and 0.23 for the north.

 

Design Scheme Control Path Diagram

 

2 High-Performance Enclosure Structure

 

Exterior Wall Insulation Method

The exterior wall insulation material uses 150mm thick graphite polystyrene (EPS) insulation boards with a thermal conductivity ≤0.032W/ (m·K). Rock wool strips with a thermal conductivity ≤0.046W/ (m·K) are used as fire isolation belts between layers, and the outer surface uses real stone paint.

 

Roof Insulation Method

The exterior wall insulation material uses 150mm thick graphite polystyrene (EPS) insulation boards with a thermal conductivity ≤0.032W/ (m·K). The horizontal fire isolation belt is made of rock wool strips, 500mm wide. A vapor barrier is laid under the insulation layer, and two layers of 3mm+4mm thick modified asphalt waterproof membrane are laid on the insulation layer.

 

Exterior Door and Window System

The exterior windows and exterior door windows use triple-glazed double-cavity (5 high-transmission low-e + 16Ar + 5 + 16Ar + 5 low-e warm edge strip) tempered insulating glass. The heat transfer coefficient K of the exterior windows ≤1.2W/ (m·K), the self-shading coefficient is 0.34, and the airtightness is grade 8.

 

Entrance Door

Steel composite energy-saving exterior door, heat transfer coefficient K ≤1.2W/ (m·K), airtightness is grade 9, and fire integrity ≥0.5h.

 

Airtightness Design

A simple building shape and node design is adopted to reduce or avoid nodes with difficult airtightness treatment. Airtight materials suitable for node airtightness treatment are selected. Special node designs are carried out for parts prone to airtightness problems, such as door openings, window openings, electrical junction boxes, and pipeline penetrations.

 

Thermal Bridge-Free Design

The exterior walls and roof use an exterior insulation staggered bonding method to avoid seams in the insulation material. The insulation layer is fixed with thermal break anchors, and the components in contact with the exterior wall are treated with thermal breaks (polyurethane thermal insulation pads). Sleeves are reserved at the locations where pipes pass through the exterior walls, leaving sufficient insulation space.

 

HVAC System

A ring-controlled integrated unit system is adopted. Each household is equipped with a ring-controlled integrated unit with a sensible heat recovery efficiency ≥75%. It also has heating and cooling functions in winter and summer, bearing the indoor heating and cooling load. In spring and autumn, it can only provide fresh air or natural ventilation. Each household's bedroom and living room are equipped with an intelligent control panel with temperature adjustment and air speed adjustment functions, which can realize the adjustment of temperature and air volume of the environmental integrated unit. The environmental integrated unit sends air to the bedroom, study, and living room through air ducts. Exhaust vents are set in each bathroom, and centralized return air vents are set in public areas. Rooms without return air vents or overflow vents have a 20-25mm gap between the inner door and the ground for return air. When the CO2 concentration, PM2.5, etc., exceed the standard, the fresh air volume is automatically adjusted to supplement fresh air.

 

The environmental integrated unit consists of an indoor unit, an outdoor unit, and a control system. The kitchen uses a pressure-reducing exhaust duct for roof exhaust and adopts a ventilation method of mechanical exhaust and natural replenishment. The bathroom is equipped with a forced start switch to force the start of the environmental integrated unit to achieve ventilation.

 

Each ring-controlled integrated unit is equipped with a temperature control device and an indoor air quality testing device, which can automatically control the operation of the fresh air unit according to the return air temperature, CO2, and PM2.5 concentration.

 

In passive ultra-low energy consumption residential buildings, the indoor design temperature is set at 20℃ in winter and 26℃ in summer. The heating, cooling, and ventilation systems are set according to the recommended values to avoid excessively high or low temperatures. When the indoor temperature falls below the set value in winter, the outdoor unit starts heating; when the indoor temperature rises above the set value, the outdoor unit stops heating. In summer, when the indoor temperature exceeds the set value, the outdoor unit starts cooling; when the indoor temperature falls below the set value, the outdoor unit stops cooling. When the indoor CO2 concentration reaches 1000 ppm, the fresh air fan starts; when the indoor PM2.5 concentration reaches 75 μg/m³, the fresh air fan's internal circulation starts to filter and purify the indoor air.

 

 

Control Operation Strategy

 

1 Heating Condition (Mixed Air Mode)

 

In passive ultra-low energy consumption residential buildings, the indoor design temperature in winter is ≥20℃ (occupancy rate above 70%), and the integrated unit uses the heating mode. When the indoor humidity and temperature are low, the integrated unit starts heating; it takes 7-10 days to reach thermal equilibrium. After the indoor temperature reaches thermal equilibrium, the integrated unit operates at a low gear (1-2 gears) or in automatic mode. The owner sets the temperature according to their comfort requirements. It is recommended to set it between 20-22℃. After operating in automatic mode, the host automatically adjusts the heating frequency of the external unit according to the indoor temperature to achieve energy saving and emission reduction.

 

2 Cooling Condition (Mixed Air Mode)

 

In passive ultra-low energy consumption residential buildings, the indoor design temperature in summer is ≤26℃, and the integrated unit uses the cooling mode. Compared with the heating mode, the time for the integrated unit to reach thermal equilibrium in cooling mode is shorter, and the indoor temperature is expected to reach the design requirements within 1-3 days. After reaching the requirements, the integrated unit continues to operate at a low gear (1-2 gears) or in automatic mode. The owner sets the temperature according to their comfort requirements. It is recommended to set it between 24-26℃. When operating in automatic mode, the host automatically adjusts the cooling frequency of the external unit according to the indoor temperature to achieve energy saving and emission reduction.

 

3 Internal Circulation Mode

 

The internal circulation mode is only activated when the outdoor air quality is severely exceeded, such as heavy smog or thick smoke. The internal circulation mode does not affect the normal operation of the cooling and heating modes; it only closes the fresh air function. This not only ensures indoor air quality but also reduces the frequency of filter replacement and extends the filter's service life.

 

4 Pure Fresh Air Mode

 

The pure fresh air mode is used during the transition seasons. In spring and autumn, when the temperature is comfortable, this mode allows you to enjoy fresh air without opening windows, ensuring indoor cleanliness. Of course, when the air quality is good, you can also choose to turn off the integrated unit and open the windows for natural ventilation, reducing energy consumption while ensuring comfort.

 

 

Energy Efficiency Control Indicators

 

Shishou City is located in an area with hot summers and cold winters. According to the national "Technical Guidelines for Passive Ultra-Low Energy Consumption Green (Residential) Buildings (Trial)", the energy efficiency indicators for the ultra-low energy consumption building of the "Litian Lake畔" project are detailed in the table below.

 

Technical Standards for Ultra-Low Energy Consumption Buildings of the "Litian Lake畔" Project