The Build Series – Energy Star ZERH and High Efficient Lighting, 48V DC LED’s
Energy Star ZERH builds require energy efficient lighting, the requirements can easily be met with AC LED light bulbs these days. In the Blue Barn builds it was decided to use a DC 48V low-voltage lighting/fan/safety system for the ZERH builds instead of the typical high voltage. There are many advantages to a 48V DC low voltage system.
The first and most obvious is the wire cost. In most residential homes, there is no need for the heavier gauge wire of the past for super-efficient LED lighting. An old 5 bulb chandelier that would have been 300 watts of light bulbs is now 40 watts with AC LED bulbs. 48V DC drops that even farther to 30 watts with no flicker. That is an 90% reduction in power use. Instead of 14/2 wire, we can now use 18/3 wire for the runs to the switches and 18/2 or 20/2 wire for the runs to the lights or fans. This is about 70% less copper needed for the lighting/fan/safety circuits of the home. The lighter wire is also easier to run compared to the heavier wire.
DC low voltage eliminates multiple AC circuits that require arc fault breakers from the main panel, which is a cost and hassle-saving advantage. Plus, it is safer than 120V AC since the DC loads are managed with redundant smart power supplies.
The ATX LED system we have chosen to use also uses standard light fixtures converted for DC use. We have a wide variety of DC light fixtures that we can order through ATX LED or CLEANLIFE. Most AC light fixtures can be converted to low voltage DC use.
Another big advantage! Light bulbs will now last 20+ years as advertised! That saves even more money for the homeowner. The number 1 failure point of high voltage AC LED lights is the AC to DC driver in each light. They heat up and burn out, causing the light to be thrown out even though the LED element is fine. In my last home, we had to replace about 25% of the AC LED lights in the first six years. While the AC LED bulbs are considerably less expensive than they used to be, it still costs money to replace the AC LED bulb that doesn’t last the advertised 20+ years. The number of light bulbs kept from landfills could be staggering!
The DC low voltage system can be installed with regular switches or smart switches and it installed like a typical high voltage AC system. It can be installed by a low-voltage or high-voltage electrician which gives us more contractors to get competitive bids from. We can leave it up to the customer to decide how smart they want their lighting system, and since it is low-voltage, it is simple for the customer to change out switches by themselves in the future. Everything is color coded and only 48v.
Now, the big question is cost. We calculate that using the low voltage 48v DC lighting vs. a high voltage AC lighting system will save about $1,000 per home on the electrical installation for the ZERH builds.
Since total loads have to be calculated for this system, we also know what the total load for all of our DC light/fan system is. With everything turned on the total load on the 48V DC system is 493 watts, that’s it.
The big takeaway is that the highly efficient LED light systems required for the ZERH build are no upgrade cost anymore. By switching to the low voltage 48 DC LED lighting instead we can actually save money on the electrical install.
