Design of a Nearly Zero Energy One-Family House in North-Centre Italy

Abstract

The thermal design of a nearly zero energy one-family house, in North-Centre Italy, is described. The house has a timber frame, a wood-fiber thermal insulation for the roof and a wood-fiber plus YTONG blocks thermal insulation for the lateral walls. Forced ventilation with high efficiency heat recovery is employed. Heating and cooling is provided by an air-to-water heat pump connected to floor radiant panels. Domestic Hot Water is supplied by a thermal solar collector and a heat pump for DHW. The electric energy for the heat pumps and for the forced ventilation system is supplied by PV collectors, which provide also most of the electric energy for lighting and appliances. The thermal design is based on dynamic simulations performed through the code TRNSYS 16.

Nomenclature

A :

Area (m²)

a :

Dimensionless coefficient

c :

Specific heat capacity (J/(kg K))

F :

Partial load factor

f :

Dimensionless coefficient

F _R :

Heat removal factor

G :

Number of days in a month

Q :

Thermal energy (kWh)

$\dot{Q}$ :

Thermal power (W)

R :

Thermal resistance per unit area (m² K/W)

t :

Time (s)

U :

Transmittance (W/(m² K))

V :

Volume (m³)

$\dot{V}$ :

Volume flow rate (m³/s)

η :

Efficiency

θ :

Temperature (°C)

λ :

Thermal conductivity (W/(m K))

ρ :

Density (kg/m³)

τ α ₀ :

Effective transmittance-absorptance product at normal incidence

φ :

Slope (°)

ψ :

Linear transmittance (W/(m K))

add :

Additional

c :

Control

C, nd :

Cooling, need

cr :

Cooling, real

d :

Distribution

DHW :

Domestic hot water

e :

Emission, external

ecd :

Emission, control, distribution

f :

Heated floor

gd :

Ground

HP :

Heat pump

hru :

Heat recovery unit

int :

Internal

L :

Overall

mth :

Month

SW :

Supplied water

TOT :

Total

u :

Useful

ve :

Ventilation

yr :

Year

0 :

Waterworks

100 :

100 % of nominal frequency

15 :

15 % of nominal frequency

COP :

Coefficient of performance

CR :

Capacity ratio

EER :

Energy efficiency ratio

EP :

Energy performance indicator

SCOP :

Seasonal COP

SEER :

Seasonal EER