Design and Assessment of a Net Zero Energy House

Abstract

This work presents an attempt to solve the shortage of power generation for a house in Lebanon, as a renewable energy-based case study, and aims to supply a neighborhood with electricity, hot water, and seasonal heating and cooling. The study starts by choosing the right orientation and construction materials of the house, in order to minimize energy and water usage and reduce outside noise transmission, by optimizing the thicknesses of acoustic and thermal insulation materials used to achieve the desired requirements. An exergy analysis is conducted to assess various system components and the overall system efficiency through multiparametric variables. A comprehensive economic evaluation is carried out where several techniques are utilized and the optimization of several factors achieves maximization of renewable energy usage by reducing exergy destruction and minimizing cost is carried out. The ultimate goal of the study is to produce a sustainable net zero energy house with reduced CO₂ emissions.

Nomenclature

Cp:

Specific heat (kJ/kg-K)

$\dot{\mathrm{C}}$ :

Stream cost rate ($/s)

$\dot{\mathrm{s}}$ :

Entropy (kJ/kg-K)

$\dot{\mathrm{h}}$ :

Enthalpy (kJ/kg)

$\dot{\mathrm{P}}$ :

Power (kW)

P_O :

Reference pressure (kPa)

p:

Pressure (kPa)

To:

Reference temperature (°C)

T:

Temperature (°C)

$\dot{\mathrm{m}}$ :

Mass flow rate (kg/s)

$\dot{\mathrm{Q}}$ :

Heat rate (kW)

$\dot{\mathrm{w}}$ :

Power rate (kW)

gen:

Generator

abs:

Absorber

eva:

Evaporator

con:

Condenser

hex:

Heat exchanger

in:

Inlet

i:

Inlet stream

e:

Exit stream

PV/T:

Photovoltaic/thermal

turbine:

Wind turbine

Ve:

Wind velocity

Ex:

Exergy

Cpow:

Power coefficient

ηtrans:

Efficiency of transferring Dc to Ac current

in:

Inlet

s:

Solar

W:

Water

cell:

Photovoltaic cell

h_c:

Heat transfer coefficient

ir:

Interest rate

N:

Yearly hours of operation

R:

Universal constant (kJ/kg-k)

n:

Life cycle in years

c:

Cost of stream ($/GJ)

R_e :

Real part

Turb:

Turbine

Capc:

Capacitance

Trans:

Transmission

at:

After turbine

bt:

Before turbine

Pmp:

Pump

k:

Stream number

gener:

Generated

SFPK:

Stream component fueling the product

GL:

Overall

ψ :

Exergy efficiency

η :

Efficiency

ε :

Heat exchanger effectiveness

λ :

Turbine blade tip speed (m/s)

x :

Concentration of the desiccant by mass (%)

° :

Degrees

ω :

Turbine rotational speed (rpm)

α :

Absorption coefficient