Manual J, S & D — Shreveport & Northwest Louisiana

Shreveport Manual J Load Calculations

Shreveport sits at the corner where Louisiana’s Gulf humidity runs headlong into Texas heat and Arkansas winters. It is a two-season market that the Gulf Coast never has to deal with — genuinely hot, genuinely humid summers, and winters that drop cold enough to make heating a real part of the sizing conversation. A square-footage estimate handles neither side correctly.

A proper Manual J load calculation determines the actual heating and cooling loads for a Shreveport home — using Red River valley design conditions, not a Gulf Coast assumption and not a Texas assumption. The result is a load number that works for both seasons and gives the humidity its due weight in the cooling calculation.

Shreveport’s summer cooling load arrives through multiple paths simultaneously — solar gain, conduction, infiltration of hot humid air, and internal gains. A Manual J accounts for each one separately, room by room.

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Why Shreveport is a two-season sizing problem

Shreveport occupies a climate position that demands respect for both seasons. Summer design temperatures push into the mid-to-upper 90s with Red River valley humidity that keeps the latent load high from May through September. But winter drops the design temperature to around 22°F — cold enough that heating is a genuine part of the equation, not an afterthought.

That two-sided demand is what sets Shreveport apart from the deeper Gulf markets. New Orleans and Houston are cooling-dominated; you can almost ignore the heating side. Shreveport cannot. A heat pump sized only for the summer cooling load may not have adequate heating capacity when January delivers a hard freeze. A gas furnace sized only for the coldest morning is probably oversized for the cooling coil it shares.

The humidity is a year-round variable here too. Unlike drier climates where humidity management only matters in summer, Shreveport’s proximity to the Gulf keeps relative humidity elevated into the shoulder seasons. The latent component of the cooling load is real, and it is exactly what a rule-of-thumb estimate ignores. See our overview of hot and humid climate load calculations for how moisture changes the sizing math.

What goes into a Shreveport load calculation

We run a full room-by-room ACCA Manual J in WrightSoft Right-Suite Universal using Shreveport’s actual design conditions — not Gulf Coast numbers, not Texas numbers:

Factor	Why it matters in Shreveport
Summer design temp	Mid-to-upper 90s°F — the sensible cooling load is large and drives equipment sizing.
Winter design temp	Around 22°F — a real heating load that must be sized alongside the cooling load, not ignored.
Latent (moisture) load	Calculated separately from sensible cooling — Red River valley humidity means moisture removal matters on both sides of the summer peak.
Solar gain through glazing	Intense summer sun makes window orientation and SHGC a top cooling driver; each glazing counted separately.
Insulation & envelope	The envelope has to perform in both extreme heat and genuine cold — both sides of the calculation depend on it.
Infiltration & ventilation	Hot, humid outdoor air entering the home is a continuous latent and sensible load in summer; cold dry air in winter.

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Heat pumps in Shreveport — the balance point question

Heat pumps are increasingly common in Louisiana markets, and Shreveport’s winter design temperature of around 22°F raises a question that warmer climates never have to answer: does the heat pump have enough heating capacity when temperatures drop?

Most heat pumps lose capacity as outdoor temperature falls. At 22°F, a unit sized only for the summer cooling load may be delivering 60% of its rated heating output — which may or may not be enough to meet the calculated heating load. The Manual S equipment selection process checks the balance point — the outdoor temperature at which the heat pump’s output meets the home’s heating demand — so there are no surprises in January.

For variable-speed systems, this analysis is even more important. A modulating system that performs beautifully in mild weather may still need its cold-climate heating capacity verified against Shreveport’s winter design conditions before equipment selection is complete.

The housing stock across greater Shreveport

The Shreveport-Bossier City metro has a wide range of housing construction — older brick ranches and craftsman homes in the established South Highlands and Garden neighborhoods, post-war construction throughout Bossier City, and newer suburban development spreading south into Keithville and west toward Greenwood. Each presents a different load profile.

Older construction often has minimal attic insulation, single-pane windows, and ductwork sized for equipment that no longer exists. These homes routinely have loads significantly higher than their square footage suggests — particularly the infiltration load, which compounds the latent problem in a humid climate. See our overview of airtight homes and ventilation for how building tightness affects the load calculation.

Newer suburban construction is better built but often features open floor plans, high ceilings, and west-facing glass that drives the afternoon cooling load well above what builders expect. In both cases, a Manual J built from actual construction documents is the only way to size correctly.

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Areas we serve around Shreveport

We provide residential Manual J load calculations, Manual S equipment selection, and Manual D duct design across the Shreveport-Bossier City metro and northwest Louisiana — remotely, with no site visit required.

We also serve Baton Rouge and New Orleans across Louisiana, and work nationwide. Every project uses the same ACCA methodology — the climate inputs change, the rigor does not.

Who we work with in the Shreveport area

HVAC contractors use our calculations to pull permits, select equipment with confidence, and deliver comfort that holds up through both Shreveport’s humid summers and its cold snaps. A permit-ready Manual J, S, and D package means fewer questions at the inspection desk and a defensible record if the homeowner has questions later.

Builders and architects need the load data before mechanical rough-in and equipment specs are committed to. We coordinate with the mechanical drawings so the system that gets installed matches what the house actually requires.

Homeowners replacing a system or investigating a comfort problem get an independent answer before a contractor quotes equipment. Knowing the right size before the conversation starts — including the heat pump balance point question — is worth more than the cost of the calculation.

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Frequently asked questions