The PNE manager labelled it ‘not very good’ as an 81st minute goal from Rams substitute Ravel Morrison settled the game in the home side’s favour.
North End had centre-half Liam Lindsay sent-off just after the half-hour mark for bringing down Tom Lawrence who was clear on goal.
Referee Geoff Eltringham got his red card out again 10 minutes into the second half to dismiss Derby midfielder Max Bird for a bad tackle on Ben Whiteman.
Rarely did PNE offer an attacking threat, either with 11 or 10 men, and it was hard to claim they deserved something from the game.
Lowe said: “It was not very good to be honest, I’m disappointed.
"First of all the sending-off killed our momentum. We had started quite well and then we had to change and adapt a bit.
"We got to half-time at 0-0 which was okay. When Derby lost their man I thought we would get on the front foot and it would affect them more than it would affect us.
"They needed to find a win and basically they found it and we didn’t.
"The red card changed the game plan. We changed shape today and went for something a bit different to give opportunities and rest one or two.
"I thought we did well to keep it to 0-0 with 10 men, we had a plan in place to keep nice and tight, resolute and compact, try and play on the break.
"Then when they got their man sent-off we thought it would be more disappointing to them. That didn’t prove the case.”
Derby had three bites at the cherry to score their winner, North End keeper Daniel Iversen saving from Curits Davies and Luke Plunge after a corner had come into the box.
But when the ball fell to Morrison, the Jamaica international rifled home a shot.
Lowe said: "The goal was just comical really. Daniel Iversen made two fantastic saves and then Alan Browne has scooped it back in when we could allow it to go out.
"We haven’t picked it up and they have a shot on goal. Every goal conceded is a disappointment but to concede it the way we did wasn’t good.
"I thought the game was going to be seen out as a 0-0, we were cagey and I thought Derby were definitely cagey.
"We didn’t look like we were going to score and I didn’t really see Derby scoring unless it came from a mistake.
"Daniel made two fantastic saves but we have to make sure we see that out and clear it.”
This was a third game in a row PNE had failed to score, something which Lowe admitted was a worry.
"I’m always concerned about goals, I want my sides to be scoring goals and at the moment you are looking to see where they are coming from,” said Lowe.
"We haven’t really had clear-cut chances, if I was put my house on Cameron Archer getting a clear chance I would say he was going to score.
"Emil Riis on his day, coming inside and scoring. Ched Evans is a bit different, he can finish but doesn’t get as many chances.
"You want the ‘eights’ to pop up, Alan Browne and Daniel Johnson, with goals.
"It is a bit of a concern that we aren't finding a way and no one is really taking it on.”
Attention now turns to the big derby with Blackpool on Tuesday night, a game being played on what would have been Sir Tom Finney’s 100th birthday.
While it is a mid-table clash in terms of position, Lowe knows there is so much riding on it locally.
Lowe said: "I have put the onus on the captains to lift themselves in there. We can do our bit as coaching staff but when they are in the dressing room, there are lads who know these derbies inside out.
"I’m new to it, I’m getting to know it, I know it’s a big game and it’s a big game for the fans and football club.
"We will put the game plan together and hopefully we will get a better response because we need it.
"It is the biggest game of the season since I’ve come in. We can’t go up, we can’t go down, we want to get as many points as we can to finish as high as we can.
"That would give us a good mantel for next season about what we want to do.
"It is a massive game for our fans, they want to see a reaction from the last time we played against them.”