AHU Engineering Report

Air Handling Unit — Full ASHRAE Compliance Analysis

ASHRAE 62.1-2022 ASHRAE 90.1-2022 HoF 2021 Ch.26 ISO 16890
📋Project Information General▾
🌤Outdoor Design Conditions ASHRAE 169-2021 Climate Data▾
P_atm = 101.325 · (1 − 2.25577×10⁻⁵ · z)^5.2559 [kPa]
→ z = 500 m → P = — kPa
📖 ASHRAE Fund. 2021 Ch.1 Eq.3
☀ Summer Design — 1% Exceedance
❄ Winter Design — 99.6% Exceedance
☀ Summer OA — Auto Calc
P_atm—kPa
Dew Point T_d—°C
❄ Winter OA — Auto Calc
P_atm—kPa
Dew Point T_d—°C
🏢Indoor Design Conditions ASHRAE 55-2020 / 62.1-2022▾
☀ Summer Set-Point
❄ Winter Set-Point
💨Airflow — Ventilation Rate Procedure ASHRAE 62.1-2022 §6.2▾
V_bz = R_p·P_z + R_a·A_z [L/s] → V_oa,min = V_bz/1000·3600 [m³/h]
→ V_bz = —
📖 ASHRAE 62.1-2022 §6.2.2 Table 6-1
ASHRAE 62.1 OA Adequacy — V_bz = — m³/h —
🏭AHU System Schematic System Overview▾

Air flow path: Outdoor Air → Filters → Crossflow HEX → Coils → Supply Fan → Supply Air
Return path: Exhaust Air → Crossflow HEX → Exhaust Fan → Outside

OUTDOOR AIR SUPPLY AIR G4 Filter F7 Filter CROSSFLOW PLATE HEX ε_s —% ↑ Exhaust ↓ OA Supply COOLING COIL CHW 6/12°C HEATING COIL HHW 80/60°C FAN Supply EXHAUST OUT RETURN AIR EXH FAN ΔP 40+75 Pa SHR=— Q=—kW SFP=—
📊Psychrometric Analysis ASHRAE Fund. 2021, Ch.1▾
P_ws = 0.61078·exp(17.269T/(237.3+T)) [kPa]
Buck 1981 — Summer: — | Winter: —
📖 ASHRAE Fund. 2021 Ch.1 Eq.6
W = 0.621945·φ·P_ws / (P − φ·P_ws) [kg/kg]
Summer: — | Winter: —
📖 ASHRAE Fund. 2021 Ch.1 Eq.20
h = 1.006·T + W·(2501 + 1.86·T) [kJ/kg_da]
Summer: — | Winter: —
📖 ASHRAE Fund. 2021 Ch.1 Eq.32
ρ = 1/v v = 0.287055·(T+273)·(1+1.608W)/P
Summer ρ: — | Winter ρ: —
📖 ASHRAE Fund. 2021 Ch.1 Eq.28
📊 Psychrometric Chart (SI) — State Points & Processes P_site = — kPa
① OA Summer ② OA Winter ③ After HEX (Summer) ④ After HEX (Winter) ⑤ Supply Air / After Coil ⑥ Room / Exhaust
☀ Summer — Outdoor Air
T_db—°C
P_ws—kPa
W—kg/kg_da
h—kJ/kg_da
ρ—kg/m³
T_dew—°C
AH—g/m³
ṁ_supply—kg/s
❄ Winter — Outdoor Air
T_db—°C
P_ws—kPa
W—kg/kg_da
h—kJ/kg_da
ρ—kg/m³
T_dew—°C
AH—g/m³
ṁ_exhaust—kg/s
🔄Crossflow Plate HEX — ε-NTU Method ASHRAE HoF 2021 Ch.26 Eq.26.56▾
ε_s = 1 − exp[(NTU^0.22/C_r) · (exp(−C_r·NTU^0.78) − 1)]
C_r = C_min/C_max | T₂ = T₁ + ε_s·(T₃−T₁) | T₄ = T₃ − ε_s·C_r·(T₃−T₁)
NTU=— | C_r=— | ε_s=—%
📖 ASHRAE HoF 2021 Ch.26 Eq.26.56 + ASHRAE 90.1-2022 Table 6.5.6.1
☀ Summer Mode
T₁ OA inlet—°C
T₃ Exhaust inlet—°C
C_r——
NTU——
ε_s calculated—%
T₂ OA leaving → coil—°C
T₄ Exhaust leaving—°C
Q_s recovered—kW
ΔP supply—Pa
❄ Winter Mode
T₁ OA inlet—°C
T₃ Exhaust inlet—°C
C_r——
NTU——
ε_s calculated—%
T₂ OA leaving → coil—°C
T₄ Exhaust leaving—°C
Q_s recovered—kW
ΔP exhaust—Pa
ASHRAE 90.1-2022 CZ4A — Summer ε_s ≥ 50% —
ASHRAE 90.1-2022 CZ4A — Winter ε_s ≥ 50% —
🧊Cooling Coil — Summer Design ASHRAE Fund. 2021, Ch.18▾
Q_s=ṁ·1.006·ΔT·1000 Q_l=ṁ·ΔW·2501·1000 Q_tot=Q_s+Q_l [W]
V_chw=Q[kW]·1000/(4186·ΔT_chw) [L/s] | d=√(4V/(π·v_w))·1000 [mm]
T_in=— (from HEX) | Q_s=— | Q_l=—
📖 ASHRAE Fund. 2021 Ch.18 | h_fg=2501 kJ/kg | cp,w=4186 J/(kg·K)
🧊 Cooling Loads
T_in (from HEX)—°C
Q_sensible—kW
Q_latent—kW
Q_total—kW
SHR——
Condensate—L/h
Face Area—m²
🚿 CHW Piping
ΔT CHW—°C
V_chw—m³/h
Pipe ID—mm
Nominal DN—
🔥Heating Coil — Winter Design ASHRAE Fund. 2021, Ch.18▾
Q_heat = ṁ · 1.006 · (T_out − T_in) · 1000 [W] | V_hw = Q·1000/(4186·ΔT) [L/s]
T_in=— (HEX winter) | Q=—
📖 ASHRAE Fund. 2021 Ch.18
🔥 Heating Loads
T_in (from HEX)—°C
Q_heat—kW
Electric equivalent—kW
♨ HW Piping
ΔT HW—°C
V_hw—m³/h
Pipe ID—mm
Nominal DN—
⚙Fan Sizing & Performance Curves ASHRAE 90.1-2022 §6.5.3▾
P_shaft = V·ΔP/η_fan [W] | P_motor = P_shaft/η_motor | SFP = P_motor/V_m3h ≤ 2.5
📖 ASHRAE 90.1-2022 §6.5.3.1 | Motor IE3 (EN 60034-30)
⬆ Supply Fan
Flow—m³/h
Static Pressure—Pa
P_shaft—W
P_motor—kW
BHP—hp
SFP—W·s/m³
ASHRAE 90.1 SFP ≤ 2.5 —
⬇ Exhaust Fan
Flow—m³/h
Static Pressure—Pa
P_shaft—W
P_motor—kW
BHP—hp
SFP—W·s/m³
ASHRAE 90.1 SFP ≤ 2.5 —
⬆ Supply Fan Characteristic Curve
⬇ Exhaust Fan Characteristic Curve
🫧Filter Sizing ISO 16890 / ASHRAE 52.2 / EN 1822▾
G4 Pre-filter ISO Coarse 60–80% ASHRAE MERV 7-8 ΔP clean: 40 Pa Replace: 200 Pa Qty: — pcs F7 Bag Filter ISO ePM1 ≥55% ASHRAE MERV 13 ΔP clean: 75 Pa Replace: 350 Pa Qty: — pcs H14 HEPA EN 1822 — 99.995% Cleanroom / Medical ΔP clean: 250 Pa Replace: 600 Pa Qty: — pcs G2 Exhaust ISO Coarse <60% Return air pre-filter ΔP clean: 20 Pa Replace: 100 Pa Qty: — pcs → Supply Flow → ← Return Flow ←
Supply Filter Train — G4 → F7 → H14(opt.)
G4 Supply Qty—pcs
F7 Supply Qty—pcs
H14 HEPA (opt.)—pcs
ΔP G4+F7 (clean)—Pa
Exhaust Filter Train — G2 → G4
G2 Exhaust Qty—pcs
G4 Exhaust Qty—pcs
📄Engineering Summary Report ASHRAE Compliant Design▾
AHU Engineering Report
Location · Engineer · Date
💨 Airflow
Supply—m³/h
Exhaust—m³/h
Outdoor Air—m³/h
ASHRAE 62.1 Min—m³/h
🔄 HEX
ε_s summer—%
ε_s winter—%
Q recovered (S)—kW
ASHRAE 90.1—
🧊 Cooling
Q_total—kW
SHR——
CHW Flow—m³/h
CHW Pipe DN—
🔥 Heating
Q_heat—kW
HW Flow—m³/h
HW Pipe DN—
⚙ Fans
Supply fan—kW
Exhaust fan—kW
Total power—kW
ASHRAE 90.1 SFP—
✅ Compliance
ASHRAE 62.1 OA—
90.1 HEX ε_s—
90.1 Fan SFP—
References: ASHRAE Fundamentals Handbook 2021 Ch.1 (Psychrometrics) · ASHRAE HoF 2021 Ch.26 (Heat Exchangers, ε-NTU Eq.26.56) · ASHRAE 90.1-2022 §6.5.3 (Fan SFP) · §6.5.6 Table 6.5.6.1 (Energy Recovery CZ4) · ASHRAE 62.1-2022 §6.2.2 (Ventilation Rate Procedure) · ISO 16890-1:2016 (Air Filters) · EN 1822-1:2019 (HEPA) · Buck (1981) Pws equation