Building performance, energy audit, energy services, weatherization, air sealing, performance contracting

How to Size a Heating and Cooling System – 101

Older space conditioning systems (more than 10 years old) are often unreliable and much less efficient than a modern system. When it’s time for a new replacement, choosing one of the correct size (heating and/or cooling output) is critical to getting the best efficiency, comfort, and lowest maintenance and operating costs over the life of the new system. Some national surveys have determined that well over half of all HVAC contractors do not size heating and cooling systems correctly.

The most common sizing mistake is in oversizing. This not only makes the new system more expensive to install, but also forces it to operate inefficiently, break down more often, and cost more to operate. Oversized heating equipment also often creates uncomfortable and large temperature swings in the house. Oversized air conditioners (and heat pumps) do not run long enough to dehumidify the air, which results in the “clammy” feeling and unhealthy mold growth in many air-conditioned houses.

In this post, I’ll discuss

Incorrect Sizing Methods
Why Most Older Systems Are Oversized
Manual J and D: The Correct Way to Size a System
A Special Case: Sizing Steam Heating Systems
Steps a Good Contractor Should Take to Size a System

Read below for the full post, if you have any in-depth technical questions, feel free to leave a comment or ask them in our geothermal technical help community. 



11 Tips for Proper Manual J Calculations for Geothermal Contractors

Many geothermal and general contractors pay a subcontractor to perform Manual J calculations when its required.  Accurate heating and cooling loads are absolutely critical to properly designing a geothermal system (See 4 Steps to Designing a Geothermal System) and according to Ryan Carda creator of Loop Links, its the number one more common mistake that geothermal designers make in the design process. If you’re new to geothermal, download the geothermal survival kit to get a better understanding of how the technology works.

In many states, it is now a requirement to perform a manual J calculation to pull a permit for any HVAC job. If you are a general contractor or geothermal installer it will pay to do your own Manual J calculations because so much of the job depends upon accurate loads.  Continue reading to learn the 11 tips to creating the best Manual J calculations for your job.


How to Build a Renewable Energy Division in an Existing Building Company – PART 1

A lot of residential and light commercial renewable energy work is starting to be picked up by general contractors, like Jamie Leef of S+H Construction in Cambridge. Why? General contractors are in a unique position to pick up this work because they’re used to managing projects, sales, and it supplements their existing business.

Beginning in September, I am going to be working with one of my best friends in Maine to create their renewable energy division. My friend Gilbert took over his father’s residential construction company. It’s a small local company in coastal Maine that has a repuation for building high quality, energy efficient homes.

I’m going to keep a journal of the journey on Heatspring Magazine because many of the issues we’ll be dealing with are common for everyone in the industry. What am I going to be discussing? Everything that a small business must do to make money; establishing our marketing and sales strategies, performing site visits and creating sales proposals, applying for incentives, the design process and lastly, the installation process. My goal is to be 100% open and share everything we learn. I have absolutely no fear that me sharing this material will mean less business for us. In fact, I feel it will sharpen our business strategy, writing has a tendency to do this, and it will help other contractors like yourself. Read below to get this specifics.  If you like this idea, have any questions, or are working on a similar project, feel free to leave a comment or ask me on HeatSprings facebook page.


What the Heck is Home Performance? Seriously. One Contractor to Another.

Paul Eldrenkamp has been a residential remodeling contractor for 26 years. Energy efficiency work has been the competitive advantage that has gotten his business through the current recession. He has a knack for breaking a very complex topic down into some simple language, and he keeps his eyes on the business impact at […]

Increasing Focus on Building Efficiency Will Have Consumers Talking

“A house needs to breathe,” but how much does it need to breathe? Recently developed standards and increasingly affordable measurement tools have made it easier to answer that question with precision, and we’re now able to target one of the largest sources of heat loss/heat gain in existing buildings. Efficiency and weatherization are growing in mass-market appeal because they are a good investment – even in the short term. But, like geothermal heat, and unlike solar and wind, they are not a form of ‘conspicuous production.’  They do not necessarily sell themselves. Beyond dollars and cents, you need a way to ‘jazz up’ efficiency and weatherization for the wide range of your customers. You need to be able to justify building these services into a larger business strategy, so here are some things for you to consider:
Selling Efficiency
Beyond the money, your potential customers will often ask, “Why?” or “Why now?” Or they may say, “Why not a granite countertop first?” Or so many other things. To answer them, it helps to think globally, and locally. Building efficiency is essential to the nation, sure, but it’s also essential to the well being of local communities. It is, probably, one of the easiest ways of doing well by doing good.